All relevant information should be migrated to http://themes.tiki.org
Another color scheme generator found, thisone is very nice:
For all the template and css hackers around here is a link to a nifty Color Scheme Generator:
Or check out a cool color palette generator, that can extract palettes from images.
Another colour styling tool: http://meyerweb.com/eric/tools/color-blend/
Also take a look at StylesList for existing themes in Tikiwiki.