NASA
Sts 114 Shuttle Mission Imagery
It is probably safe to say that this site holds the largest collection of images from the Space Shuttle Discovery's 2005 mission. 625 images in all can be found here as well as a generous description for every image.
Other
Space Shuttle Discovery
This personal site contains a number of interesting pictures of the space shuttle Discovery. You will view interesting shots of crew cabin, launch pad and more. Interesting commentary is provided.