Quake III running on a Motorola Droid was impressive. But Quake III running on the Nexus One - no physical keyboard, a souped up processor - that's downright heavy metal.
The video quality may not be great, but the gaming quality seems impressively strong running at "medium/high-ish graphics". To get around not having a keyboard, the trackball acts as the mouse while the increase/decrease volume buttons are walk forward/jump, respectively. And the soundtrack is aggressive. Couldn't ask for much more. [YouTube via CrunchGear]