Speaking as someone who finds Adobe Photoshop rather inscrutable while at the same time wishing I could perform some of the graphical manipulations it makes possible, I'm a total sucker for programs like BeLight Software's Image Tricks. Put simply, Image Tricks uses Mac OS X 10.4 Tiger's Core Image filters to enable you to apply a wide variety of neat effects to your own photos and graphics. The filters fall into a number of categories: color, focus, distortion, styling, halftone, tiling, illumination, and overlaps, along with a dizzying array of masks. New in the recently released Image Tricks 2.0 was the addition of "generators" for creating mathematically generated patterns (which I like, though I prefer patterns in my screensavers). With 2.0, BeLight also made the distinction between the free version (which does plenty for most people) and a pro version that adds more generators and filters. Now we're up to 2.2, which adds even more filters and generators.