Muro is an amazing digital painting application that only requires a modern web browser.
It does not use Flash or any special plugin. HTML5, pure and simple, like similar online tools such as Harmony or Sketchpad. Meaning what? Meaning that you can use it not just on your computer, laptop or desktop, but also on your iPad or iPhone / iPod Touch, for example. Here is a sample of something I tried on my laptop:
And, as a bonus, if you have a Wacom tablet installed, you can take advantage of additional features provided by the browser plugin, available on the Wacom website.
If you want to try you hand with some other related programs, here it is a selection of drawing applications for your browser, based in several technologies (html5, flash, java…): Cloudcanvas, Sumopaint, Pixlr, SketchPad, FlashPaint, ScribLink, Myoats, FlockDraw, ScribblerToo, Queekypaint, ImaginationCubed and a generous selection reviewed at Make use of.