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.
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
PowerShell Studio - PowerShell Studio is the easiest GUI designer and script generator available.
TreeSize - TreeSize tells you where precious disk space has gone to.
GNU Bourne Again SHell - Bash is the shell, or command language interpreter, that will appear in the GNU operating system.
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.