I use Photoshop and have used GIMP as well as Paint Shop Pro but I'm really interested in learning Corel Painter and I just want to know it's use in the industry if it has much of one :)
Painters representation D: Alchemy/Photoshop here. If what you're after is just a program that will give you a natural media look & feel I'd suggest giving ArtRage a try, really convincing results and much cheaper than painter.