Lisa's Video Frame Capture Library is an interesting place. She's captured still from an eclectic bunch of movies and posted them on her web site. One series is of course the Lord of the Ring's of New Line.
Easily navigated you can search by text links or thumbnails to find the movies and scenes you are looking for. There are even character galleries for individual searches as well as some unused scene caps. Upon this posting the gallery was last updated in January of 2009.
A good solid collection of screen caps can be found at the Lisa's Video Frame Capture Library.