Tidy Up is tool that can help you reduce hard-drive clutter by identifying duplicate files on any mounted disk. This utility's multipane interface has a bit of a learning curve, despite its new "Basic Mode," and the app's comprehensive search criteria and system of smart and manual "baskets" may not be immediately intuitive to casual users.
Anyone who spends time getting familiar with Tidy Up and its three- step approach, however, will find that it's a powerful tool for identifying and dealing with duplicate files, whether you want to delete them, move them, or back them up onto alternate media. In addition to complex searches using standard file attributes, Tidy Up also offers specialized tools for searching through Mail, iTunes, iPhoto, and Aperture (including by EXIF data). Given its price and rich feature set, Tidy Up may not fit the bill if you're looking for a fast, simple way to conserve disk space, and unfortunately you might have a hard time deciding given the 10-item limitation of the trial version.
For administrators and other users who need to manage large numbers of disks and files--especially those dealing with lots of images--Tidy Up can be a potent and versatile tool.