(3.5) Anyone use a nice encounter generator?

[Sylivin]

I am starting up a gestalt Dark Sun-esque campaign (dying world, high powered) and l'm looking for an encounter generator where I can toss in a CR rating and get multiple beasties for that encounter that add up to that CR. Alternately maybe something that lets me pick beasties by CR and then totals it up on the fly. Being able to print them out or even generate them on the spot would be very spiffy as well.

Soo.. anyone use something like this already?