It would depend on your hosting needs. For single pics less than 1024 kb, use http://www.imageshack.us For pics up to 8500 or 9500 (I forget right off hand)... use http://www.ho5t.us and for a portfolio type deal... use http://www.photobucket.com
http://imageshack.us is the best i have found. Im sure there are other good ones, but they are quick and easy