I may end up getting a buttkicker after they go way way - waaaay - down in price. The reason why is because it seems like it can add an effect to games that has a more arcade feel to it.
Namely, I remember an older game (1999 era or so?) called Hydro Thunder, whereas anytime you bumped into a rock or something, you can actually feel that happen due to the strong subs that were built into the seat itself. I thought that particular effect was really cool, and it did it without blowing your ears out even though the speakers were about 6" away from you.
If this can add that kind of effect, then that would be pretty nice. Not $500 nice, but maybe $100 nice. Especially given that I prefer my sound setup to be at lower volumes than most people, and that this would be a creative way to add effects in the 5hz-30hz range where you are (obviously) supposed to feel it more than hear it.
EDIT: Oooh...the gamer version is $49 after rebate on amazon, with free shipping...Hmmm...soo tempting to pull the trigger on that one...Only thing that bothers me is no RCA LFE channel support that I can tell (or is there?)
http://www.amazon.com/Philips-BK-GR-Buttkicker-Gamer/dp/B000AOTLP6