Free iPhone wallpapers are rarely outrageously beautiful, so when I find a collection of them that are, I go nuts with them.
Whereas before my best resource was Poolga, I now have a second option.
TypeNuts also has a reserve of gorgeous, rich, high-res images, and like Poolga, they're totally free.
But that's not even my favorite part: the wallpapers on TypeNuts all share a theme of using type and font-based designs.
I'm an addict, and this only my latest fix.