I tried to get Moodle (http://moodle.org/) to run on one of our Windows servers, but getting to run Apache/PHP/MySQL on Windows Server was more headache than I care for... So I have taken the unprecedented step of running some of our production stuff on a Linux server, and I have still not gotten over it.

How about running .Net on Linux? Visual Studio? SQL Server? I'm sure it can be done, but it sounds like a big cluster of you-know-what...