A list of Screen capture sites and Stock photo sites. Many more to come i'm sure. ^^

DreamsTime; Community of Royalty Free Images and Stock Photos
Free Photo Archive Public Domain Photos and Images
Corbis
Free Images
Free Stock Images
Gettyimages.com
Romance Book Covers
Fotosearch
Stock Xchng
Project Gutenberg
Cap Central
Nitwit! Blubber! Oddment! Tweak! (HP movie screencaps)
Simple Obsession