Most free programs are going to be available mainly for the X11 environment, such as MacGIMP. I wouldn't call this a simple program, though--it's quite complex. If you'd like a simpler program, AppleWorks at $79 should do the job, and you get a word processor, spreadsheet, etc. to boot. Or you could buy Photoshop Elements for $89 and get a nearly full-featured photo editor. Or for about the same amount, you could subscribe to .mac for a year and download Photostudio X for free.