I go Greek with mine, either real historical figures, or myth/demigod/gods, and there is real meaning behind the names assigned...
Argos: The Mini Core Solo for Security and Home Automation.
Janus: My C2D MacBook Pro everyday toter.
Archimedes: The 4x3ghz Mac Pro used for video and 3D.
Pythagoras: The outgoing iMac G5 (to be replaced by another Mac Pro) used for Logic Pro music recording.