You don't have to be a graphic design major, or "know a guy who knows a guy who can get photoshop for dirt cheap". Pixlr is free and there is no catch. Given that this is a browser friendly editor, you can download a Firefox add-on designed for "grabbing" pictures off the net and editing the image on your browser in a matter of seconds. I edited my twitter profile avatar with the add-on:Polyvore.com. Yes, they are $325 Alexander Wang shades. I know, they look just like the real thing!
For tips on how to use the editor, check out the Pixl blog. My favorite tool has to be the brush tool. With a growing brush collection, you can transform your image with brushes ranging from doodles to vector stalks, true stroke of genius.