http://www.onemotion.com/flash/sketch-paint/
http://www.sumopaint.com/home/ http://thisissand.com/
http://www.flashpaint.com/paint.php
http://mugtug.com/sketchpad/
http://slimber.com/index.php?r=1
http://www.enchantedlearning.com/painting/
http://www.psykopaint.com/painter.html
http://www.dreezle.com/(not that fun but might be for you)
http://www.crayola.com/coloring_application/index.cfm?referrer=/index.cfm
http://bomomo.com/(real cool)
http://www.onlinesketchpad.com/
http://www.outlawsco.com/games/draw/chalkboard.html
http://www.gamesgames.com/game/Sketchpad-DX.html