Best Image Uploading App and Service?

[stlredbird]

I've been trying to find the best image hosting site that also has a great iphone app so I can upload and get links for photos straight from my iphone.

It looks like the top candidates are flickr, imageshack and picasa.

Imageshack seems a little shady b/c you don't even have to register, that just seems off to me.

Any thoughts/suggestions?

Thanks!