CCleaner - CCleaner cleans, speeds up and frees up space on business endpoints.
Glary Utilities - The No. 1 Free, Powerful and All-in-one utility for cleaning your PC
AVG PC TuneUp - Peak performance for your PC. Keeps it going for longer. - More Speed Turbo Mode
System Mechanic - System Mechanic uses patented technology to help fix PC errors and restore speed. The software is compatible with multiple versions of Microsoft Windows.
Clean Master - Some users swear by it, some call it a glorified snake oil that does more harm than good. That can be said about any snake oil, but what specific brand of snake oil can boast almost a billion downloads around the world?
Sysinternals Suite - The Sysinternals Troubleshooting Utilities have been rolled up into a single Suite of tools.