Been using my old Model B as a media player running XBMC to feed thumb drive movies to my HDTV.
Debating whether or not to replace it with the spiffy new quad-core model
and let the old one turn my weather station into a web-accessible killer robot or similar.
Truth be told, I'm sure I could be doing more with it... I've just been procrastinating and waiting for the right project that offers the perfect mix of awesomeness, usability, and less intimidating coding.
While I've been given books and magazines "full of Cool Pi Projects", IMHO too much Pi stuff is pitched as either Build a stop light / Make flip book animations (ages 8 -18) or Design/Build/Code a PiCade console (full blown Linux nerd required).
The extra power of the new units (now with multitasking, woo) should open up opportunities to do more for the same price. For those who still
can't get enough horsepower out of the same form factor... See Odroid
for overkill on an itsy-bitty board.
Then there's the whole world of options available for those who want to delve into Arduino gadgetry...