>>and computer chairs (that are springy when you sit down in them)

Hmmm, I see a product opportunity. Office chairs with built-in "buttkicker" bass modules. You could probably use a smaller subwoofer and not upset your coworkers when watching DVDs at work... I mean... researching...

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8