I know I’ve done the whole megalomaniacal arch-villain thing before, but to celebrate the fact that someone has finally released a computer game wherein you play one, here are a few more related links:
Badguy, the Magazine for Villains, Archfiends, Mad Scientists and other Evildoers
Here’s a useful source for the obligatory robot army.
Handy reference to keep track of your rivals.
Some interesting ideas to distract pesky heroes.
"Five exclamation marks, the sure sign of an insane mind."
(Terry Pratchett, Reaper Man)