I submitted a hint a while ago, regarding a way to create short URLs using Perl, AppleScript and Automator, which also required that one download a package of software.
Since that hint was published, the URL service (qgf.in) went down because the owner left it to the wolves. So here's a new Service that completely eliminates the need for Perl and the download. This service uses bit.ly, but you can choose another website (make sure you get the API format [usually http://short.url/api?url=http://website.com/]) as well.
First, create a new Service in Automator. Set the top bar to read 'Service receives selected URLs in any application', and check 'Replaces selected text.'
Then drag in a Run AppleScript action from Utilities. Copy/paste the following script into the script field:
Mac OS X Hints