well, it's not so much a separate thing is that it's a feature of amps/receivers... just check out most amps for surround sound, they should have PLII (watch out for just Pro Logic....it sucks...#2 is where it's at).

i dunno, just head down to your local electronics store (Fry's, Best Buy, CompUSA, Circuit City, whatever) and check out the surround systems.

newer 7.1 receivers even have Pro Logic IIx, which upmuxes stereo streams into 7.1. i've never heard that, but i cant imagine it really being that much more exciting.

additionally, some computer speakers by Logitech have Pro Logic II, the Z-680, Z-5500 and Z-5450 have the ability to do PLII, i believe. however, there are different types of PLII (movie, music, and game) which utilize different mixing matrices; i dont think that those Logitech speakers let you pick which one you want.

yeah, those are the basics i guess