Useful Downloads:

Java, in order for ChibiPaint to work you need a recent version of Java installed on your computer. If that's not the case, get it there.

JTablet, if you use a tablet to draw, you'll need JTablet to be able to use the pressure sensitivity in ChibiPaint.

Recommended Oekaki Boards:

E-kaki.net, excellent french speaking board where ChibiPaint is available.

Misc:

ChibiPaint's official deviantART community, a good way to stay informed about the latest developments.