This site allows you to create pictures by dragging provided shapes onto the drawing board.
Several themes are provided. You can learn more about ThinkDraw here.
From Crayola try this online drawing tool with a variety of markers and stamps.
Sumo Paint is an online painting tool which offers an extensive collection of tools and some very sophisticated features.
Students over 13 who enjoy art and animation could try the Doink app for iPad and iPhone. You can create your own work, reuse work by others and share work with your friends. You can post your work to Facebook and YouTube. The DoInk Facebook page is here.
Try ‘Stardust’ on the Wonderfl site which allows users to build flash online.
Click on the image above, select Play then experiment, move the little circles around and watch what happens! Note the full screen option.