Pinta is a lightweight photoshop-style drawing and editing program. Not quite as complex and feature packed as Krita or Photoshop, yet still includes a wide variety of familiar features including, layers, adjustments, effects, clone-stamping, gradients, text and more. Users of Photoshop will feel at home with a similar tool layout and workspace.
Believe it or not, most commercially available software has a FREE twin! (Or at least distant cousin!)