Angeldogs, I like picnik-
www.picnik.com
I don't know if you can tell in my avatar, but there are really fun effects you can use to make your picture look 60s/70s-ish (photos with rounded corners, sort of kodachrome looking, faded, etc.)
It's pretty straightforward and there's quite a lot you can do with the effects, captions and cropping etc.
Word of warning-- once you start with the fun stuff you can't stop
