These sites have all been tested by yours truly...they're certainly no substitute for making your own artwork, but they are a fun way to pass some time!
SCRIBBLER is a favorite of mine...simple mouse-drawn doodles become expressive artwork with the computer-generated addition of gesture lines. http://www.zefrank.com/scribbler/
BUILD YOUR WILD SELF is a site that allows students to create human-animal combinations with pre-made choices. The graphics are nicely drawn. http://buildyourwildself.com/
BOMOMO is a fun site for creating non-representational art. Experiment with different brushes and effects, and you can print out or save your final result! http://bomomo.com/
JACKSONPOLLOCK.ORG does not give you the option to save or print, but it is fun and addictive! Click on the link at the top of the first screen, and your mouse is transformed into a dripping paintbrush. Click to change colors while you paint. http://jacksonpollock.org/
THIS IS SAND is a favorite among students...a very Zen experience. Click on the small square on the first screen for directions. http://thisissand.com/
MAKE YOUR OWN SNOWFLAKE is an entertaining alternative to folding and cutting paper snowflakes. It also shows you the steps of folding a paper snowflake if you pay close attention!http://snowflakes.barkleyus.com/index.html