FREE
For Windows
SmoothDraw
Like Microsoft Paint, but better and free
http://download.cnet.com/SmoothDraw/3000-2192_4-10199284.htmlhttp://download.cnet.com/SmoothDraw/3000-2192_4-10199284.html
GIMP
Like Photoshop
http://www.gimp.orghttp://www.gimp.org
Online
SplahUp Light
http://www.splashup.com/light/
SplashUp
http://www.splashup.com