Bit.ly is a URL-shortener like TinyURL with a host of interesting features, as enumerated in the switchAbit blog.

1. History — we remember the last 15 shortened URLs you’ve created. They’re displayed on the home page next time you go back. Cookie-based.
2. Click/Referrer tracking — Every time someone clicks on a short URL we add 1 to the count of clicks for that page and for the referring page.
3. There’s a simple API for creating short URLs from your web apps.
4. We automatically create three thumbnail images for each page you link through bit.ly, small, medium and large size. You can use these in presenting choices to your users.
5. We automatically mirror each page, never know when you might need a backup.
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A post in ReadWriteWeb, Bit.ly: Please Use This TinyURL of the Future, points out some interesting ‘semantic’ features.

“In the background, Bit.ly is analyzing all of the pages that its users create shortcuts to using the Open Calais semantic analysis API from Reuters! Calais is something we’ve written about extensively here. Bit.ly will use Calais to determine the general category and specific subjects of all the pages its users create shortcuts to. That information will be freely available to the developer community using XML and JSON APIs as well.
    As if that’s not a whole lot of awesome already – Bit.ly is also using the MetaCarta GeoParsing API to draw geolocation data out of all the web pages it collects.
    You want to see all the web pages related to the US Presidential election, Barack Obama and Asheville, North Carolina? Or about Technology, Google and The Dalles, Oregon? That will be what Bit.ly delivers if it can build up a substantial database of pages. Once it does, it will open that data up to other developers as well.”

The idea of using a URL shortening service to identify significant or interesting Web pages for further processing is a new twist. It would be great of other services with catalogs of interesting pages, like del.icio.us, did this as well. Eventually, this will be done to the entire Web, but for now, it’s too expensive. This is an interesting intermediate step.