Not really very practical to try and play, but with some good demos from esreality quite the kickass way to showcase what the droid and its dedicated graphics processing can do. With proper sound and video tweaking I've been able to get about 35 fps on average.
So how's that HID stack coming I wonder?
Android Bounty: Fully working Quake 2 and 3 ported to Droid – Android and Me
quake 3 ported to motorola droid | droid life: a motorola droid blog
download and install quake 3 on your motorola droid | droid life: a motorola droid blog
When I find some demos I'll post links, but one is included in the game.