These Utilities are either FOSS (Free and Open Source Software) or proprietary and free (usually for home users only). Please check the licensing terms carefully before installing.

LibreOffice - a free software suite: https://www.libreoffice.org/
NirSoft - miscellaneous utilities: http://nirsoft.net/
Sysinternals - miscellaneous utilities: https://technet.microsoft.com/en-us/sysinternals
Ultimate Boot CD: http://www.ultimatebootcd.com/

More links coming soon.