Drupal has a couple of modules which allow you to produce your own tinyurl.com type website - complete with your own tracking etc.
This has been extended for use by the US government at http://go.usa.com/ and the code re-released to the community.
This mainly adds statistics gathering and reporting
Unfortunately the module maintainer has chosen not to integrate these changes back into the module at drupal.org - issue here : http://drupal.org/node/520588
So now the patch doesn't apply cleanly unless you checkout an old version of the module from CVS like this