Alchemy's a freeware graphics program used for initial vector-based sketches, but by itself, I find, that it creates its own beauty. Pretty nifty brush FX too. :) (This was done in Mirror Mode. There is also a Microphone command that affects the brush when music/sound is played.)
For this course, I'm going to need every weapon I can get! To try Alchemy, you can subscribe and download it here: http://al.chemy.org/