· Indigent Academic
A second vote for SeaShore. I now use it instead of GraphicConverter. GraphicConverter is more powerful, no doubt, but SeaShore covers all my needs and as it is related to GIMP it will grow in capabilities. SeaShore is free, GraphicConverter is shareware and nags for its ~$30 (you can use it for free, but it tells you how many days you've done so every time you open it) - however shareware that is used really should be paid for...
GIMP requires an X11 setup. SeaShore is OSX universal.