Looking for a program to list all duplicate pictures and optionally delete them?
To find exact matches, I use DeDuper: http://www.niftyprograms.com/deduper.htm
Lightning fast and spot on accurate. You can let it do its thing automatically, or, as I like to do, watch it pop up the duplicates and click to confirm one at a time. It's really amazing.
Another one that comes highly recommended is Dup Detector: http://www.freeware-guide.com/rareware/DupDetector.html
You sacrifice a bit of speed, but it is more flexible in that it can find "close" matches too, where the .jpg isn't quite an exact match, but is close enough.