Most pictures that get uploaded on other sites are usually found da fan and are then postato on here, but te could always try places like Tumblr, Photobucket, ect.
If you're starting to collect pictures, I'll start te off! ;-)
I think that the best way to find loads an nice Johnny Depp's pictures is to cerca in Google (Images) "Johnny Depp",and you'll find his best pictures all together!