I'll just mention this in case any packagers want a challenge. I.mage is a graphics editor that's very nice for pixel level editing. It's at http://www.memecode.com/image.php
I've tried building it on Linux before, but haven't had much luck with the results. Maybe someone else wants to give it a try. It should be pretty lightweight and I think it depends mainly on the LGI and LCMS libraries mentioned/linked to on the page. There are some other interesting programs at the site too if anyone wants to check them out.