It's a simple toggle to prevent your computer from showing screensaver and going to sleep. Instead of going to "System Preferences" each time you want make sure your computer will not sleep for a period of time, you just toggle Caffeine on.
It's useful when watching movie. As a software engineer, sometimes I need to run something from command line that requires long hours to complete over SSH where you need your machine to be up or else it will disconnects from the network and will close all your session.
If you have an extra monitor hooked up to your Mac and you want to adjust the brightness and/or contrast of you monitor, you have to control it manually through your monitor's physical buttons.
MonitorControl enables you to control brightness and/or contrast of your external monitor from your Mac and can even control by your Mac's brightness keyboard key.
Mac Spotlight on steroids.
It's a better search tool for Mac compared to Mac's own Spotlight. It can do all cool stuffs like calculation, file search and always can do better.
Can search and index files faster, you can add custom search.
4. Memory Clean 2
Simple and easy way to free your computer memory. It also shows which application takes the most memory.
Free mouse pointer highlighter great for doing online presentation or web tutorials.
Don't agree with my list or have anything that I should include? Please let me know!