lilURL - A Free/Open Source Clone of TinyURL
lilURL is a simple PHP/MySQL script for generating lilī URLs. It's similar to TinyURL, Shorl, MakeAShorterLink, etc, but you can run it on your own server ((which is, yeah, pretty much the same thing as TightURL, but that didn't exist when I wrote lilURL)). Requires PHP and MySQL; supports mod_rewrite.
lilURL is released as Free software, under the GNU general public license.