If you're working on a multi-media project (film, slideshow, pres ...), you'll be happy to add some music !
Monotonik gathers quite a few electronic music (mainly created on computers, some on Amiga ). Most of them are usable as lounge music, and they are under Creative Commons non commercial license.
And if you want music for your commercial projets, I recommend Jamendo : you can buy good music at a good price. In particular, there's a great offer (in my opinion) to get music in your place (restaurant, shop, ...) for 48€ a year.
Lastly, you may get music completly free of rights (public domain or any other kind) on Wikimedia Commons, but that's mainly classic music (or old) when rights have expired.