For once, BitsDuJour have a decent software giveaway
Its basically a PC program for Artists and artistic enthusiasts.
4/5 star with decent reviews on cnet.
TwistedBrush Pro Studio 17 provides artists with over 5,000 brushes, as well as realistic media, to enable the creation of traditional artwork using new technology.
With TwistedBrush Pro Studio 17, you'll enjoy access to photo cloning, tracing, masks, particles, filters, and more.
There are plenty of opportunities for experimentation, thanks to a variety of brush shapes, patterns, and textures, and great flexibility, featuring support for integrated scanners and Adobe-compatible plug-ins.