If you're into using Corel Painter, this is a very worthwhile subscription-based forum which I highly recommend:

http://www.digitalpaintingforum.com/

Until October 1 all POTF forum members that are already paid have a chance to update their membership for only $40 for 2 years. October 1st the forum fee will be $49/year or $75/2 years...add years to your membership now before you lose the great deal.
Get it while it's hot!