If you haven't visited James Gurney's blog, you should. He has lots of amazing and inspiring stuff on there. For someone with out much formal painting training it's a wonderful resource. I keep a link to it in my inspiration folder also know on bad days as the why-do-I-bother folder.
This is a piece that I did for "Art by Committee" but thought I'd post it here too. It's definitely inspired by my son. Visit Gurney Journey for the specifics of the challenge.