Artweaver is one of the best natural media bitmap applications out there, well certainly for the price (FREE!). The tools don't produce effects perhaps quite as realistic and organic as say Art Rage, but the results are stunning if you know how to make the tools work for you.
I was just noticing that Artweaver is an amazingly functional bitmap creation and editing tool. Though it is chiefly known for its fancy brush tool's ridiculous number of customizations, it has almost all the mainstay features that programs along the line of Adobe Photoshop have. It has layers, filters, masks, and so on. Today I realized that it has enough of these general tools to make it a totally feasible option for anyone on a budget. Most people think of the GIMP when suggesting a free bitmap editor. I personally can't stand the GIMP, primarily for its horrid interface (ew, yuck, gross!). Artweaver should be mentioned alongside the GIMP for free solutions for bitmap editing. The only thing Artweaver lacks that I like to have is vector paths. Otherwise it has all the necessities.
For the record, Artweaver's painting tools put all mainstream programs to absolute shame, including Adobe Photoshop. The presets and controls are almost too much. If you play around with different settings, I have no doubt anything is possible. My problem is finding a reason to use them. About all I can do is fiddle and doodle, since I can't really think of anything purposeful to draw. This drawing is one of those mindless doodles, getting lost in space and time while experimenting with the endless tools.