http://www.freesound.org In case anyone hasn't been to this site, it has a huge database of sounds uploaded by users, under a Creative Commons license (you have to mention the names of users you got sounds from) which is very useful.
I posted this because I remember how hard it always was for me to find good sounds. (When I've uploaded one of my earlier animations I'll show you what I mean.)
Found this looking for a good electric hum to use for the Light Maze menu.
