Cdw - cdw: ncurses interface for GNU/Linux command line CD/DVD tools
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
CompuCom - Technology Solutions for the Digital Workplace
TreeSize - TreeSize tells you where precious disk space has gone to.
Sirius - An open-source clone of Siri from UMICH
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.