So you need a image editor and you want something more than the free stuff in iPhoto but somehow you don't think that PhotoShop at $700/copy really is what you need. Enter Acorn by Flying Meat. It is a $50 image editor that, as they put it, is "The Image Editor for Humans". Now some of my best friends are designers who really need Adobe's Photoshop and I that does not make them "non-human". However, it can take years of meditation and psychotherapy to develop the ninja skills required to operate Photoshop effectively. So I have been on a quest for some time now to find a reasonably priced image editor that I can use without having to read a 300 page manual.
I once heard it said that 80% of Photoshop users access less than 20% of the features of the software. So this category of software makes sense to me. For less than 10% of the cost of Photoshop, users get access to the bulk of the features they would use in a more robust software package.
I won't do a full review here because I just downloaded the new version, but I am hopeful as the new version has 64 bit support (should be getting much faster) and runs only on OSX 10.6 (Snow Leopard). You can go here to see other new features. Or go here to try an older version that runs on OSX 10.5 (Leopard).
If you have Snow Leopard and want to try it out for free, you can download a demo at their web site.