WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.

Tune Sweeper - Show duplicates in your Music library. Automatically select which duplicates to keep and delete based on your preferences. Remove duplicates with one-click from your iTunes or Music app library.

WizTree - WizTree quickly finds the files and folders using the most space on your hard drive. It scans the MFT (Master File Table) instead of crawling the entire disk which makes it very fast.

Leawo Tunes Cleaner - Leawo Tunes Cleaner is a powerful iTunes cleanup tool, which can help you to delete duplicates in iTunes and get album artwork for iTunes music files.With it,you can clean up iTunes music library fast and comprehensively.

SpaceSniffer - SpaceSniffer is a freeWare (donations are welcome) and portable tool application that lets you understand how folders and files are structured on your disks.

Dupe Eliminator for iTunes - iOS, iPad, iPhone, iPod Touch, iTunes, iTunes software, Software for iTunes, mobile iOS apps for iPad, iPhone and iPod Touch. Remove iTunes duplicates. Stream iTunes Music Library. Super iTunes Suite of useful tools.