http://www.ambientdesign.com/artrage.html

I bought this program to help bring out a (non-existant as it turns) out graphic ability.  But fortunately my children love using it.  I could write loads about it but if you visit the website you'll be able to see what can be done with it, oil paint emulations, stencils and all sorts of other cool tools.

There's a gallery and some forums which people use to post their images (you need to sign up and login to see the images I've discovered).  Anyway if you have a spare minute have a look, it's terrific.