have i ever told you how much i _love_ the gimp? maybe one of these days i'd like to save up for photoshop, but gimp (gnu image manipulation program) is free (both as in beer and as in speech), is nearly as powerful (not quite the range of filters and no true color space) and is growing steadily (including splitting into several subprojects).
it just amazes me, every time i fire up a good open source/free program, to see what people can make just by cooperating and volunteering their time and energy to an idea.
if you've never used gimp (even if you're hooked on photoshop) you might give it a try some time. you might like it, might find something useful it has to offer, or might find something useful you could offer the gimp community.