Magical Jelly Bean Keyfinder - The Magical Jelly Bean Keyfinder is a freeware utility that retrieves your Product Key (cd key) used to install windows from your registry. It also has a community- updated configuration file that retrieves product keys for many other applications.
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
ProduKey - Recover lost product key (CD-Key) of Microsoft Office 2003, Office 2007, Windows XP, Windows Server 2003/2008, Windows 7, and more.
TreeSize - TreeSize tells you where precious disk space has gone to.
Recover Keys - Recover Keys is product keyfinder program which can recover lost product keys for Windows 8, 7, 10, Office, Exchange, Adobe Photoshop and many-many 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.