Here's an idea—build a subwoofer into a wall to save some space, and turn the deadspace behind your drywall into a resonating chamber. Actually, I'm not certain these subs aren't sealed around the back. It would make more sense if they were, because any serious thumping could start pushing fiberglass out your wallsockets.
Two 8-inch subs with special aluminum cones anodized to give it a ceramic coating. Supposedly second in strength only to diamond. Rigidity = good for nice, taut, bass. Oh, all that room you're saving? You'll need to use to rackmount the 500-watt RSA-500 amp that powers it. $500 for the sub, $750 for the amp. Oh CEDIA, you're sooooo for rich guys.
Klipsch Wall Subwoofer RW-5802 [audioholics]