Ever since StumbleUpon spun itself off from eBay last April, it’s been reinventing itself at a rapid pace. In June, it launched Su.pr, its own URL shortening service, but that was just an interesting new product. Today, it is starting to roll out a major redesign that recasts the service as a social search engine “somewhere between a Twitter and Google,” says founder Garrett Camp.

About 8 million people a month use StumbleUpon, says Camp, to bookmark and share the best sites on the Web. More than 35 million Web pages have been stumbled, and now the company has indexed them all to make them more searchable. The homepage has also been simplified to show you a stream of pages recently stumbled by people you know. New StumbleUpon users will see the redesign immediately, while existing users can switch by clicking here.

What is it with all the toolbar copycat craziness lately. First, there was Digg going after StumbleUpon with the Diggbar. Then StumbleUpon, which already had a toolbar, introduced a new toolbar/URL shortening service called Su.pr.

Now, micro-blogging service Tumblr is getting in on the act with its own toolbar which it is calling TumbleUpon. Could they try to be more blatant in ripping off StumbleUpon? The toolbar has a random Stumble-like shuffle button which randomly takes you through different Tumblogs in a similar way that StumbleUpon’s toolbars do. On the right there is a heart button if you want to “like” a page, a reblog button and a button that takes you to your own Tumblr dashboard.

Su.pr, StumbleUpon’s URL shortening service, has come out of closed beta. StumbleUpon, which was recently freed from eBay’s clutches, tossed its hat in the URL shortening ring earlier this year. We first heard about Su.pr in March when StumbleUpon CEO Garrett Camp Tweeted about it. Su.pr, like other shortening tools, lets you shorten a URL and share it across Twitter, Facebook, and StumbleUpon.

The nifty part of Su.pr’s service is that it gives you a dashboard to help you keep track of how many times your su.pr links have been shared, across which services. You can see how many times each link has been clicked on and retweeted (along with the number of followers for each retweeter). It also lets you schedule shared links across those services for any time you want.

What is the best way to sift through a stream of information? The list view seems to be the most popular because it is information-dense and easy to scan, but it can be overwhelming. More visually appealing ways to manage data are needed. Twine, a site which lets you collect and subscribe to different interest feeds, just introduced a new way to wade through its streams.

The new Flash visualization presents your stream of shared links as a deck of headlines which you can shuffle through (see video below). A slider along the bottom, lets you cycle through the deck by time, and arrows underneath let you move sequentially, or you can just click on a deck in the background to move it forward. If you want to learn more, you can flip each deck to read a snippet and link to the full detail page. The semantic tags associated with each item also show up on the side and can be clicked on to navigate through the deck.

Any self-respecting Website these days has its own URL shortening service for easy syndication of links across Twitter, Facebook and other status streams. There are services such as bit.ly and TinyURL. Digg has its controversial Diggbar (which helped lift unique visitors by 20 percent). Hell, even we use our own custom short URL domain (tcrn.ch) via Awe.sm.

Now, StumbleUpon, which was recently freed from eBay’s clutches, is rolling out its own URL shortening service, Su.pr. It is in closed beta, but we have 250 invites for the first TechCrunch readers to enter the promotional code: suprtc

Earlier this month we reported on eBay’s spinoff of StumbleUpon, a company it owned for a little less than two years. Ebay bought the company for $75 million in May 2007. Unknown until now, though, was the spinoff value of StumbleUpon. According to a source close to the transaction, it was $29 million.

New investors Sherpalo Ventures, Accel Partners, and August Capital joined StumbleUpon founders Garrett Camp and Geoff Smith in purchasing the company back from eBay. Outside investors put in 85% or so of the $29 million, we’ve been told, with Camp and Smith making up the rest.

eBay was paid $25 million in cash for StumbleUpon and retains a 10% interest in the spun off entity. $4 million remains in the company to fund operations.

So StumbleUpon, a social bookmarking site that lets users browse and discover new websites by clicking a button, was a subsidiary of eBay for just less than two years. The acquisition made the startup’s founders extremely wealthy, given that they raised just $1.5 million in venture capital, and sold for $75 million.

You’d think that the founders (Garrett Camp, Geoff Smith and Justin LeFrance) would be quite content to go into semi-hibernation at eBay and contemplate their vacation homes for years to come. But like so many already-wealthy entrepreneurs, some fire kept driving at them to keep themselves challenged. It may be the deep rooted insecurity that leads most entrepreneurs to try to build companies in the first place – getting bought doesn’t necessarily give them the self confidence they thought it would. Or it may a simpler explanation – the certain knowledge that StumbleUpon hasn’t yet become whatever it is eventually destined to be.

So when the opportunity came for the founders to buy the company back from eBay and start over, they took it. The struggling eBay had been looking to sell off StumbleUpon for months, even hiring investment bank Deutsche Bank to help them get back their $75 million, but there were no takers. That left the door open for the founders to buy it back themselves.

Back in September, we reported that eBay was attempting to sell off StumbleUpon, the website recommendation service it bought for $75 million in 2007. That didn’t happen. And now the company has been spun off to start life over as an independent startup, backed by new investors and the original founders.

The new company is led by co-founder Garrett Camp, who now steps into the CEO role. Co-founder Geoff Smith also joins Camp in returning to lead the company. The company is backed by Sherpalo Ventures, Accel Partners, and August Capital. David Hornik from August Capital and Sameer Gandhi of Accel Partners join the board.

StumbleUpon is preparing to launch a shortURL service (a web service that provides short aliases for redirection of long URLs, like TinyURL or Bit.ly) in the next couple of weeks called su.pr.

Founder Garrett Camp announced the new service on Twitter without any description of what it might be on March 3. In an email exchange he says it will be a shortURL service to share StumbleUpon links on sites like Twitter and Facebook and that it will be launched in a week or two. The site currently redirects to StumbleUpon.

Digg is planning its own similar service, which we covered late last month.

A super-secret Digg toolbar has been spotted in the wild. We tracked down a beta tester who gave us the skinny on its features. The toolbar lets you Digg or Bury the page you are on, and shows how many Diggs it has already received. There are also links to show related pages, as well as more pages from the same source voted highly by the Digg community or marked as up and coming.

Then there is the “Random” button which works like StumbleUpon. It takes you to a randomly-generated page based on your past input and overall Digg voting. By the prominence of this button, it appears that is a feature Digg will be trying to highlight. Users can also share the page via Facebook, Twitter, or email via icons at the top. A drawer slides down to expose additional functionality.

Now, here where it gets interesting. For each page, the toolbar creates a shortened URL similar to TinyURL or bit.ly that starts instead with http://digg.com/. . . followed by a six-character code such as “http://digg.com/d1gVha.” When you share a page via Twitter or Facebook, it is that shortened URL which is used. And in fact, for the beta testers, the toolbar can be wrapped around any page simply by sticking “http://digg.com/” in front of any URL, which then gets converted into a shortened version.

Mixx is steadily growing, and they’re hoping to spur even greater traffic increases with a completely revamped website. But every social news service is showing growth, and Mixx actually appears to be lagging if you compare publicly available data.

Last time we wrote about Mixx, they were touting healthy traffic numbers and boasting the fact that Hitwise report suggested that its users are more mainstream than those of their main competitor Digg. Today, the company says its visitor numbers have increased to about 7 million per month (citing January figures), which is up from 5.8 million in October 2008.

Meanwhile, all the big social news and discovery services are showing healthy growth, and Mixx appears to still play in the minor leagues. Take a look at this snapshot from Compete, for example, which show Digg is thriving and Reddit is steadily outpacing Mixx.

In other Mozilla news, Firefox hit a major milestone today with the one billionth download of add-on software for the browser. That feat took three and half years.

Many of those downloads are never used more than once or twice, of course. But there is no doubt about it that Firefox is major software platform. Just look at StumbleUpon, it was built on top of Firefox.

Deutsche Bank is still out there trying to find a buyer for eBay’s StumbleUpon business, we’ve heard from new sources (we first reported on this on September 18). But there’s one problem: while eBay wants to unload the business, they aren’t willing to sell it for less than $75 million, the price they paid for it in May 2007.

StumbleUpon’s 2008 revenues are estimated to be $6 million or so.

eBay has denied the sale attempt, but there are too many people who’ve seen the deal book and have heard Deutsche Bank’s pitch. The big question is, will it sell?

Israeli blogger Tal Siach, one of the authors of the Walyou blog, seems to be one of the few people who can actually access the new, toolbar-free version of StumbleUpon. The new version was set to launch to everyone on Wednesday, but so far everyone I’ve spoken with is still on the old design, which requires the downloaded toolbar to function properly. Lucky for us, though, Tal is in, and wrote a review of what he sees.

One nice trick: if you want to see the new javascript toolbar in action, click here and it should work. You can stumble on to other pages from there.

Tal’s post is below:

Recommendation engine StumbleUpon has been facing some tough times lately: earlier this month we reported that eBay was looking to sell the startup less than 18 months after acquiring it (the company refuses to comment). And its traffic has been showing signs of stagnation (though the number of registered users to steadily rise). But tonight, the site is launching a new feature that may very well turn things around: a long awaited install-free web toolbar.

Update: CEO Garrett Camp says that usage of the service isn’t stagnating – the unique views have leveled off because users tend to Stumble without returning to the site’s homepage, so their hits aren’t recorded.

StumbleUpon has long been hindered by the fact that it requires a browser plugin that users have to download and install. Such plugins create a large barrier to entry, as they are time consuming and tend to be associated with malware. These problems are magnified by the fact that StumbleUpon’s purpose isn’t immediately obvious – many users have to actually try it out before they understand what it does (for the uninitiated, it uses an algorithm based on your preferences and other users to direct you to websites that you’ll find interesting).

In May 2007 eBay acquired website recommendation engine StumbleUpon for $75 million. Now, less than a year and a half later, they’re trying to unload it according to a source with knowledge of the sale process.

eBay has hired Deutsche Bank to find the right buyer, says our source, but the asking price is unknown. It’s not certain that eBay will be able to sell it for the price they paid – In July StumbleUpon had 1.3 million worldwide visitors and 25 million page views. Twelve months earlier the service attracted 4.4 million visitors and 31 million page views (Comscore). Google trends shows stagnation over the last year as well.