SequoiaView - SequoiaView is a featured rich application that comes with the visualization technique to provide you a single view of files and documents that are stored in your hard drive.
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
DiskBoss - A file manager with a focus on storage side of things: Monitoring, classing, storage, duplicate...
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.
DiskSavvy - DiskSavvy is a free, fast and easy-to-use disk space analyzer utility allowing one to analyze disk...
Baobab Disk Usage Analyzer - Baobab Disk Usage Analyzer is one of the light-weight disk analyzers that offers you a chance to view and monitor the disk usage & folder structure without any hassle.