WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
PowerShell Plus - Learn how to learn and master PowerShell fast with an interactive learning center, a powerful IDE, pre-loaded scripts, and a PowerShell Editor… all for free.
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.
PowerShell Studio - PowerShell Studio is the easiest GUI designer and script generator available.
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.
GNU Bourne Again SHell - Bash is the shell, or command language interpreter, that will appear in the GNU operating system.