If you're in search of some great screengrabs of some memorable movies, check out these sites:
Mise En Scene 101 - great site
Period Movies - great reference on historical costumes
The Black Island - nice hodgepodge of memorable scenes
Frame Filter - great site
The Indy Experience - great place to get your Indiana fix!
Picturas - nice gallery
And this gallery I just started:
Film Bytes
Enjoy!
