bit.ly Pro service provides custom short URLs powered by bit.ly. Publishers and bloggers will be able to use their own short domain names to point to pages on their sites. Users and publishers benefit from the additional transparency that this private-label service provides. When you see a short URL like nyti.ms, you know the destination web site before clicking on the link. The service includes all the bit.ly features users and publishers have come to expect. Placing a simple “+” at the end of any bit.ly link (including these white-label, bit.ly-powered links) takes you to real-time information about that page and how it is being shared: how many people clicked on that particular link, where they came from, and more. For publishers, the new service allows them to keep their brand visible while maintaining access to bit.ly statistics. Just sign up for a Bit.ly account and find a way to register the domain you want to use for your link shortener. Point your domain to the IP address Bit.ly gives you, and Bit.ly does the rest. You also get all of the analytics services you've come to expect from Bit.ly's non-pro package. The cutoff for a free URL shortener is 10,000 URLs shortened per day. If you're expecting more traffic than that, you'll have to contact Bit.ly for a commercial account.
More info: Bit.ly Pro