Short URLs are a necessity with the rise of micro-blogging. They also seem to have an added SEO benefit.
Dany Sullivan has a great piece on them at search engine land.
bit.ly: It offers all the key features you’d want in a service, with nice stats that show number of clicks over time, what sites are referring traffic to your twitted URL, locations clicks are coming from and Twitter conversations using the URL. It’s also the default in three of the four major clients — or three of the major clients, if you exclude Twitter itself.
tr.im: Offers all that bit.ly does other than not being built into Twirl. Tweetdeck support is coming soon. Stats are nice. Bit.ly perhaps offers more drilldown on the referrer front, from my fast review. Remember, a more in-depth review of tracking stats will come in the future.
cli.gs: Offers the same as the others above, though it is not built into either of the major clients TweetDeck or Twhirl. You do get TweetFeed support. Stats include showing which search engines have spidered your links. There’s a nice “social media mentions” section that show clicks coming off My Yahoo, FriendFeed, Google Blog Search and others.
More Choices
Snipurl / Snurl / Snipr / Sn.im: You kind of want them to pick a name and settle on it (like Sn.im). The service is currently in three clients, but it’s to be dropped from TweetDeck. Within Twhirl, it also uses the long Snurl.com domain. If you want sn.im URLs, you have to go outside the client to make them. Stats are simply the number of clicks — it’s not in the same class as services above. Finally, ZoneAlarm flagged it as spyware. It’s not, but that’s something to consider in case your visitors are running that software and trying to click on your links.
budURL: Being dropped from TweetDeck. Stats look extensive, if you want to pay. One of the longest domain names of any service.
Short.ie: Originally I had this down as not recommended, as it issued a 302 redirect. They got in touch with me and said not so! I tested again, and they are issuing 301s. They also provide custom URLs –I missed that. Both have been updated. Finally, they say that Twitterfeed support is coming. That with basic stats make them a nice alternative choice. However, they still can’t handle URLs with parameters (I tested that again, and it’s still an issue).
kl.am: Not built into any clients and the stats are fairly rudimentary.
POPrl: Semi-basic stats, being dropped from TweetDeck. No custom URLs.
idek.net: Very basic stats only, being dropped from TweetDeck. No custom URLs.