WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
MobaXterm - Enhanced terminal for Windows with X11 server, tabbed SSH client, network tools and much more
TreeSize - TreeSize tells you where precious disk space has gone to.
ConEmu - ConEmu-Maximus5 is a full-featured local terminal for Windows devs, admins and users. Get better console window with tabs, splits, Quake style, copy+paste, DosBox and PuTTY integration, and much more.
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.
Cygwin - Cygwin is a set of tools that provide Linux and POSIX functionality to Windows.