ArtRage

ArtRage is a painting software package for Windows or Macs.

The complete version is $25 but the free version  has lots of the same features.    "With ArtRage you can paint with oils, sketch with pencils, sprinkle sparkling glitter and much more. Stencils and rulers let you create precise shapes or smooth curves and straight lines freehand. Tracing and Reference images let you load photos to recreate as paintings either by eye or by letting ArtRage select colors for you as you paint. For professional users, ArtRage offers Layers, Layer Groups and Layer Blend Modes compatible with the PSD file format.

Best of all, ArtRage doesn't force you to learn complex tool settings, it lets you get right down to painting with tools you already know how to use."  

The site also provides free tutorials, forums and critiques.  Try it out the free version, post your picture on your blog and write about what you think.