If I can't actually get out and shake my booty on the dance floor, second best for me is chair dancing. But for the uber lazy there is the USB Finger Dance Mat where you can really... shake out your fingers?
Other than sheer boredom the point of this gadget is to match the mat's sequences of flashing lights that just get's harder and faster.
And if you want to image you're actually dancing it comes with a cut-out cardboard dancer to slide over your pinkies.
The embedded video clip is the old school method of finger dancing, but still goes to show what a great time you can have by letting your fingers get into a groove!