Tux Paint for the Sugar environment
and the One Laptop per Child (OLPC) "XO-1"
Newer versions of Tux Paint have been released; you can download the source-code.
Tux Paint for Sugar comes as a single bundle that includes both the main program and the add-on 'stamps' collection.
(For more information on the "Sugar-ization" development of Tux Paint, see the Tux Paint page at the OLPC Wiki.)
Tux Paint & Tux Paint Stamps.
Tux Paint 0.9.20 & Stamps for Sugar
Tux Paint 0.9.20 for Sugar Source
A small Python script has been created that you can use on the XO-1 to take the most recent webcam photos from the Journal and insert them into Tux Paint, so you can paint on them.
Did you know? Tux Paint runs right on your computer, and doesn't require Internet access.