Photosweeper LITE for Mac: Free (was $4.99) for 1 more day

This app is used to find duplicate photos from iPhoto, Aperture and Adobe Lightroom. This is the LITE version, 'full' version is a few more features:

• Finds SIMILAR photos providing 6 comparison methods. Photos are compared regardless of their sizes or formats and grouped by similarity. It allows you to find even edited photos and sequences of photo shots.

• Ability to move or copy photos you want to keep with or without bulk renaming.

http://overmacs.com/photosweeperlite.html

In the App Store link it says the deal ends December 15, which I assume is the U.S. time. Still seems to be free for us