Despite the relative lack of processing power, and the slow integrated graphics, I’ve been very impressed by how well my 1Gb Mac mini copes with running various emulators. In particular:
SixtyForce, which does a great job of emulating the N64. I’ve had great fun playing Wave Race and Diddy Kong Racing again.
Mame OS X – Arcade perfect Pacman and Galaga on a 46 inch TV 🙂