AC3 audio tracks for free?

[DaWiper]

Anyone know where about good sources for free(legal) ac3 audio tracks? Anything goes. The only I've found until now is this:

http://www.lynnemusic.com/surroundmusic.html

(I use powerdvd for playback)

I have to admit it, 5.1 audio has a great potential...

Anyway. Anyone know where to find some more?