I recently migrated my music library from one machine and platform to another, and somehow ended up with multiple copies of many of my files. Blame it on a careless click or two in iTunes (as in selecting "Consolidate Music Library"), but I ended up with a hard-drive clogging collection of music. I dreaded the task of going through my folders and deleting the dupes, but knew it had to be done. So, I looked for a free way to do it, and found DoubleKiller. The program lets you define various characteristics of files to be considered dupes, such as size and creation date — useful if you have, say, several files called notes.txt that aren't dupes. Once running, it makes quick work of scanning your drive and offers one-click deletion (or moving, if your cautious) of dupes. A pro version adds a few features, but for most purposes, the free one gets the job done.