NTLite - The Ultimate Windows Customization Tool
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Win Toolkit - BUGS: Do not post bugs in the comments.
Statista - The Statistics Portal for Market Data, Market Research and Market Studies
Ultimate Windows Tweaker - Ultimate Windows Tweaker is a freeware Tweak UI Utility for tweaking and optimizing Windows.
Montecarlito - MonteCarlito is a free Excel-add-in to do Monte-Carlo-simulations.