On February 24, Sunday, the developer room offers a great program with well known names. Talks include "What's new in Drupal 6" by Dries and myself, Drupal theming, usability and integration with web services and the ApacheSolr project, the Asset module, Drupal and MySQL high availability, just to name a few.
FOSDEM offers a great program otherwise as well, with Andrei Zmievski talking about Unicoding in PHP 6, Mark Finkle talking about Mozilla Prism (desktop web apps!) and Rogan Dawes talking about OWASP WebScarab-NG (HTTPS interception), just to name a few of my picks.
Let's meet there!