Stats - Simple macOS system monitor in your menu bar.
Drive Genius - Drive Genius is a hard drive utility that speeds up, cleans up and optimizes your Mac.
iStat Menus - "An advanced Mac system monitor for your menubar."
DriveDx - DriveDx is advanced drive health diagnostic and monitoring utility.
eul - System & Hardware and OS & Utilities
Pluto HUD - A Black Ops 2, Modern Warfare 3 and World at War modification project.