My entry for the blender game competition uses soundfx from the freesound project.
I just wanted to let you know I give full attribution to all the users.
Here's the list of credits below as it appears in the game.
datasoundsample :: "glass shatter.wav"
LS :: "camera click.wav"
Erdie :: "mega-thunder.wav"
nofeedbak :: "helicopterMix1.wav"
hello_flowers :: "choral_Pad_0003.wav"
This is my first post so I can't post a link to the competition page, but I would assume you're clever enough to find it on your own.