Mixwit makes it easy to create embeddable mixtapes (otherwise known as custom playlists). We touched upon the company a couple weeks ago as part of our Y Combinator demo day roundup but never gave it our full treatment.

A similarly-named service called Mixaloo serves up label-sanctioned tracks and requires users to buy them to hear more than 30-second previews. Mixwit differs by drawing its songs from Seeqpod, an MP3 search engine that indexes full-length tracks from mainstream artists but charges nothing for them. Granted, not all of the audio files found by Seeqpod have decent quality (many simply don’t work at all) but that’s the price of free.

Both companies facilitate the spread of mixtapes across the net, but the costlessness of Mixwit really gives it an edge (despite Mixaloo’s promise to split sales revenues with mix creators). Mixwit also provides more extensive tools for customizing the look and feel of the mixtapes themselves, lending itself to greater ranges of self-expression. Users can pick from a collection of nice-looking skins, upload their own images, and tweak several other settings such as shadow and gloss effects.

So the creation and sharing of mixtapes with Mixwit is easy and effective. But what I find particularly interesting are Mixwit’s plans to expand its offering into a more complete online media solution. The founders like to describe their company as a cross between Slide and iTunes because they plan to release an in-browser media player that will leverage the APIs of various web services to collect content found across the web. In addition to Seeqpod, they plan to include support for Flickr, YouTube, and Skreemr as well. The idea is that you’ll be able mash up different types of media (music, photos, videos, etc), bookmark them, compile them into playlists, and share with friends via widgets and the player itself.

This product has yet to make it off the drawing board (the second screenshot above is just a mockup). But the idea is promising and could be a big hit with social network junkies. It would also be a browser-based cousin of Songbird, a Mozilla-based desktop app that also strives to be the web’s media player.

Update: We’ve removed the widget once embedded here for fear of driving up someone’s hosting bill. Go here to see it.

The fledgling startups listed below will present their ideas and initial products to investors at this spring’s Y Combinator Demo Day on March 18. Of the 19 companies in this batch, 10 have already launched and only one remains in stealth mode. Most of them have been in development for only three months.

Chatterous

Chatterous connects various forms of communication so that people can message each other regardless of the form they use most. Currently the service ties SMS, email, IM, and web together so that messages sent using one technology will be received by others using any of the other technologies. This works by setting up a group on Chatterous’s website and putting down all the ways your friends can be contacted. You can then start sending messages to them immediately, meaning that they don’t even have to change their own behavior all that much. Chatterous launched in public beta last week.

Addmired

Addmired provides the AddHer and AddHim social network widgets, both of which display two user profile pictures at a time and ask users to answer certain questions about them, such as “Who’s more popular?” The founders argue that their widgets are more appealing to social network owners than other widgets, because they help drive traffic within the social networks, not siphon traffic out of them. They look to establish service level agreements with some of the smaller social networks. We covered the service in February here.

Snaptalent

Snaptalent is an advertising network for job listings that uses IP detection to determine whether website viewers work or study at particular companies or institutions. It then displays listings from employers who want to attract workers from organizations known for their talent, such as Facebook or Harvard. See our review of the service from this week here.

RescueTime

RescueTime helps individuals and businesses track how they spend their time at the computer, and consequently, find ways to become more productive. The web-based dashboard charts application and website usage over long periods of time and shows you whether you’ve been reaching your goals. So far, 278 businesses have signed up for RescueTime for a total of 26,132 seats. See our review from last May here.

MightyQuiz

MightyQuiz is a user generated quiz destination and widget provider that we covered recently. Users are encouraged to answer trivia questions from a wide range of categories. They can also submit their own questions and embed them on their sites. The site is very sticky: the average session lasts 8 minutes (or 19 questions). As a comparison, the founders claim that Slate has an average session length of 4:22 and Wired has 3:34.

Tipjoy

Tipjoy is an easy micropayment system for the web. It has been designed to cut out the steps necessary for website visitors to leave small amounts of money for content publishers, such as bloggers. The Tipjoy button placed on a website asks for only an email address and by default registers a donation of 10 cents. The service is nearing 70,000 impressions per day and the founders are exploring different models for micropayments, such as employing them to finance high definition video on the web. We wrote about Tipjoy here.

8aWeek

8aweek promises to save you hours of time wasted each week on time-drain websites like Facebook and Drudge Report. The 8aweek browser toolbar will track your website usage, remind you of how much permitted time you have left on each restricted site, and even block you from particular sites once you’ve spent too much time on them. See our review from February here.

WebMynd

WebMynd provides a visual interface for reviewing your browsing history. The founders draw comparisons to Gmail - just as Gmail obviated the need to sort messages into folders by providing effective search and tagging, WebMynd renders it unnecessary to manually bookmark sites and organized them into folders because it’s easy to search and visually flip through the pages you’ve visited. WebMynd operates as a Firefox toolbar and has already indexed 8M page impressions. We wrote about them in January.

BaseShield

BaseShield will protect Windows PCs from malicious viruses and attacks by leveraging virtualization software. Its methods improve on existing anti-virus solutions by preventing all types of attacks, not just the recognized and documented ones. The service has yet to launch.

Insoshi

Insoshi is an upcoming white label social networking platform. It will differentiate itself from many of the other social networking platforms by taking a completely open source approach (think: WordPress of social networks). The software has yet to be released.

Mixwit

Mixwit describes itself as a combination of Slide and iTunes. While it has more ambitious long-term plans, it currently provides an easy way to make sharable mix tapes with songs found through the MP3 search engine Seeqpod.

Omnisio

Omnisio will help you annotate and share videos from any website. It will also add structure to the existing video content on the web. The service has yet to launch.

Deluux

Deluux aims to become a distributed Facebook, or an inverted Ning, by relocating the center of people’s online identities to their websites, which exist outside of any one social network. The service will facilitate the distribution of personalized content around the web and help drive traffic to these personal websites. It has yet to launch.

Wundrbar

Wundrbar wants to improve upon the search bar experience by providing users with powerful inline commands. The idea is reminiscent of YubNub but Wundrbar strives to appeal to a larger audience and to incorporate functionality that helps people manage their personal online accounts in addition to searching the web.

YumDots

YumDots wants to be the go-to mobile application for finding places to eat when out on the town. Its emphasis on using interactive maps to display information about local restaurants makes it more efficient than other mobile review services like Yelp’s. The service has yet to launch.

280 North

280 North will debut with a web-based PowerPoint clone called “280 Slides” that strives to mimic the desktop experience and features the ability to export presentations to PowerPoint format. The founders’ longer term goals consist of providing a JavaScript-based development framework for building desktop-like applications for the web. None of these services, however, have been launched yet.

Kirkland North
Kirkland North wants to take an infectious campus-wide game popular at Yale and Harvard last year and spread it to other campuses around the country. The Risk-like game pits sections of campuses against each other in a virtual battle for university-wide domination. While the founders have plans to roll out an integrated solution that can serve many institutions at once, they are currently rolling out individual versions of their online service, such as one for Stanford that launched only two weeks ago and already involves 20% of the campus.

Joberator
Joberator will help employers find developer talent by encouraging computer science students to refer their developer friends, of whom they have more intimate knowledge than any professional recruiter. Incentives for personal referrals are created by employers who list the bonuses they will pay to pay those who recommend candidates eventually hired. The service has yet to launch.