Stylish online invitation site Pingg is launching a new feature today that makes the site whole lot more social. The Pingg Event Stream lets hosts aggregate real-time Twitter conversations related to their event alongside other comments, photos, and videos on the event’s web page.

The site lets hosts select a custom hashtag when creating event, which is included in the online invitation. The site will then aggregate all Tweet’s onto the event site with the given hashtag. And of course, if you choose a more general hashtag like #Oscars for your Academy Award-focused party, you’ll aggregate a general stream of Tweets about the Oscars. The stream will also feature news and updates about the event, including changes of details, other guest RSVPs, photos posted and comments.

Pingg, which launched in early 2008, was one of the initial startups to try to beatify and improve upon a concept that Evite ran with back in the day. Backed by Martha Stewart Living Omnimedia, Pingg offers users stylish invitations with design tools and a vast library of images to create the perfect online invite and site. Pingg’s customizable, ad-free event web pages also include photos, video, gift & charity registries, tools for collecting money, RSVP tracking, guest messaging and more. Event hosts can set up automatic reminder messages and thank-you notes when they are creating their invites.

Incorporating a stream into an event’s site is smart and Pingg is definitely moving in the right direction with this. Pingg already lets you post your Pingg invite directly to Facebook and message specific friends from the social network for an event. One feature missing from Pingg’s stream is the ability for a host to Tweet directly from the event’s site, which would be useful. Pingg is similar to Cocodot, an invite and event planning site that launched at TechCrunch50 this year.

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If Yahoo Local were a standalone startup, it might look like Center’d. Partly that is because CEO Jennifer Dulski used to be the general manager in charge of Yahoo Local. Center’d, which publicly launches today, is a mixture of an event-planning/invitation site and a highly targeted local search engine, with a little social networking thrown in.

The entire site is set up to do two things: plan and explore. You import your email contacts, put in your zip code, and off you go. There is a calendar view for local events, and a map view for local destinations.

The company started out as FatDoor, a failed social network for neighbors. It took the $5.5 million it raised last October from Norwest Venture Partners and Keynote Ventures, and rebooted as Center’d. The chief technology officer is Chandu Thota, previously the lead developer on Microsoft Virtual Earth. I reviewed the site last April:

Center’d is both a local search engine and an event-planning application. You can search places for restaurants, hotels, schools, museums, stores, etc., and the results appear on a Google map. There is also a calendar view. Once you connect with friends on the system their events pop up in your searches. And you can also create your own events and get your friends to help decide the details. For instance, things like the location and date can be voted on. Want to have a party by the sea? Ask your invited guests if they’d rather go to Stimson Beach or Montaro Beach, and if next Sunday is better than this Saturday. You can also assign tasks for them to sign up for: bring lobsters, bring wine, bring volleyball.

The site is perfectly serviceable and looks like it will do a decent job with both event planning and local search. The interface is heavy on Ajax, with the screen telescoping open as you go through the options. It is very similar to Pingg in that regard, except it is much more limited in what it can do. But Center’d is also not doing anything appreciably different from many other startups on the event-planning side, including Pingg, Socializr, and MyPunchbowl. It does have the local search piece, but so does Yelp, Yahoo, and Google.

Still, when you are starting out with FatDoor, anything is an improvement.

Since then, the site has been improved. Places can be saved and commented on. And it lets you connect to people through places, such as schools, stores, or museums. Social + local. Isn’t that the original definition of community?

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If you like your invite apps dead-simple, check out Mobaganda. You don’t even have to log in. Just click on start, add the name, date & time, and location, and create an event. The site, which is built on the Google App Engine, generates a Webpage that you can e-mail out to all of your friends.

Once the recipients go to the URL they can RSVP, and you can keep track via RSS or by checking back at the unique URL, which lasts for 30 days. (One downside is that no two events can share the same name during that time period).

Here’s an invite page I made in about a minute for a fake TechCrunch party:

The site generates an e-mail address that can be used to contact everyone on the RSVP list. You can also keep track of the RSVPs through Google Reader:

Or as a widget on iGoogle:

Not that we need more ways to invite friends to parties (see Pingg, Socializr, MyPunchbowl, etc.). But Mobaganda does reduce the process to its bare essentials. (The UI sensibility reminds me of Presdo). It got started as a conversation between Web developer Jason Stirman and Twitter founder Evan Williams. the question they were pondering: Would it be possible to create a better Evite, without even requiring a signup or login?”

Stirman is the creator of OhDon’tForget, a Ruby-on-Rails app that lets you send yourself pre-set reminders via text message (Time picked it as one of its 50 Best Websites last year). Stirman plans on adding text reminders to Mogabanda using OhDon’tForget (when you RSVP, you will be able to add a cell number to get a reminder the day before the event). he is also thinking of ways to add notes, maps, and other features. But he wants to keep it as simple as possible. After all, it is supposed to be the anti-Evite.

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When you get an invite from Pingg, you don’t have to click through to a Website blaring with advertisements just to find the address for a dinner. All the information is right there where it should be, in your email. Pingg’s invites are drop-dead gorgeous. A lot of care and attention has been put into the design of each one (you can choose from about 45 themes like dinner party, baby, wedding, food, travel, and eco-friendly). The invite, image, and event details all come through in your email. And you can RSVP from the email as well.

Of course, each invite is linked to a dedicated Website, where more photos, maps, videos, gift registries, and payment options exist (if guests want to pitch in to fund an event, for instance). The e-mails and Website are free. But you can also send out printed invites as postcards for $1.50 each (including postage) or send the invites as text messages to guests’ mobile phones ($1.50 for 20 messages). Gabel explains why he thinks Pingg is different in this blog post.

In addition to making money from printed invitations and sending SMS messages, Pingg has various other affiliate deals in place. If you don’t like any of the images Pingg provides for its invites, you can purchase one directly on Pingg through micro-stock photography site Fotolia (or upload your own image for free). The gift registry, which is currently linked to Amazon, offers other affiliate-fee opportunities. A ticketing feature will soon be launched, as will premium subscriptions for professional and power users. But advertising will never be part of the equation. “That detracts from the event,” says Gabel. Nobody wants to see a Weight Watcher’s ad next to a dinner invitation.

The site has some other nice touches, including guest-list management and event-reporting tools. Event hosts can set up automatic reminder messages and thank-you notes when they are creating their invites. And the RSVP options include the ability to limit an event’s capacity, or to allow invitees to bring guests or transfer their invites to others.

Pingg is based in New York City (the CEO and VP of marketing share an office with Clickable. First30Days, and independent film company PalmStar Entertainment). Its development and design team is in Toronto. The co-founders, brothers Gabel and CTO Matt Harrop, are Canadian. They founded the company in January, 2007 and self-funded it with $500,000. Then they raised an $800,000 angel round in March, 2007 led by the early-stage Actarus Funds, the investment vehicle of Stephan Paternot, co-founder of TheGlobe.com. (Paternot now runs PalmStar). At least that 1.0 money is now being put to good use.

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