I got tipped off about this site from Dave Wilson. He could kind of be viewed as my resident "Flash / Indie Development" insider.
Anyway, he forwarded over a link to 8-Bit Rocket. This is a pretty useful site. The main draw is that it has a bunch of fair use samples for use by indie game developers. The songs are all really great (although the samples are attempting to open in Quick Time, but I know several of my regular readers are big iTunes users...so that should be a problem for "those types").
The site also contains some excellent tutorials detailing some programing tips and tricks for adding the audio into your games, as well as a well written blog and some links to games that use the audio.
The danger of a site like this is that the sounds would become ubiquitous and played out. But the first time I listened to several of them, I was defiantly impressed.