Recently i thought about sound for my free flash games. I started search free and paid sounds. And after surfing the net i want share with sites what i find:
http://www.stockmusic.com/
http://www.premiumbeat.com/
http://www.newgrounds.com/
http://www.shockwave-sound.com/
http://promotingcrap.com/pages/unique-music/stockmusic/stockmusicarchive/
http://www.freesound.org/
http://www.flashkit.com/soundfx/
http://www.flashkit.com/loops/
http://www.soundsnap.com/
http://www.findsounds.com/types.html
I use http://www.sounddogs.com/
Best and widest selection out there