Simple canvas-based sketching (HTML canvas widget, Javascript)
Pic URL [MUST be from smartcg.com, else 'Save' below will fail]:
[RMB -> 'Save Image As' to save, browser 'Back' to return]
Press 'r'/'g'/'l'/'y'/'o'/'p'/'k'/'w' to switch colors, 'e' to erase,
'z'/'x'/'c'/'v'/'b'/'n'/'m' to switch thicknesses, 'q' to clear the canvas.
'B'/'W'/'G' will switch (flood) backgrounds, and 'd'/'D' is for pen down/up.
And here's a tearoff version.