... is a good program for messing with images and stuff, its sorta like a mini photoshop only free (which is always a good thing) check it out, it utilizes core image but works fine on my ibook soo woot to that http://www.belightsoft.com/products/imagetricks/overview.php
There are also a couple of programs called CocoaViewX ToyViewer and one of the Developer tools in OS X called Image Tricks All Free. Search versiontracker or macupdate.