Link Referer Plugin
I've just re-written a module I wrote for PHP-Nuke for Geeklog 1.3.8 or better. The plugin is an alternative/complimentary links system. Revolving around the standard 88x31 button links that so many sites use.
The plugin allows users to submit their site for a link on your site, with a button link provided. On link submission, a link back is generated (or set of if you have multiple buttons). The plugin then displays all button links in a nice page, and provides a phpblock function to allow you to list top referers, top visited sites, fixed selection of links or random links, or any combination of them. Full admin and stats integration.
You can see it working: Here and download it Here or on on SF.net