I'm looking into building up a new stereo system, maybe for 90% music and 10% movies. Some people have pointed me in the direction of building an "infinite baffle" subwoofer. Most of the info is here:
http://www.f20.parsimony.net/forum36475/
Basically, you cut a hole in your wall, put some large drivers in there, and make a whole room/attic/basment your sub. Or something like that. They claim it's the best sounding bass available at any price. I haven't heard one yet. My room happens to have a hole in the floor from an old heating system. And I'm up for a little DIY construction project.

I'm curious if I build this thing, will it match OK with most any main speakers I decide to go with later? From what these people say, it's great for everything and as good as it gets. Idunno...