I recently downloaded a great set of Photoshop brushes by Kyle T. Webster and of course it's appropriately called Kyle's ULTIMATE Photoshop Brush Set. I got a chance to play around with it last night and it's by far the most naturally looking brush sets I've ever seen and used! And it's totally worth the $5. You can get it here.
And here's a quick little cat guy I painted up in Photoshop.