Neofetch - Fancier version of Screenfetch that displays colors and supports more platforms.
CPU Frequency Selector - Cinnamon CPU Frequency Selector Applet
PC Wizard - THIS SOFTWARE IS NO LONGER MAINTAINED.PC-Wizard is an utility designed to analyze and benchmark your computer system. CPU and memory subsystem (caches, RAM ...). Graphics and video. Hard disks, CD/DVD, Removable/FLASH medias.
Screenfetch - Simple command-line tool that displays your distro's logo in text art form, your OS version...
Prime95 - Prime95 is a program that searches for new Mersenne prime numbers.
Speccy - Speccy - find the details of your computer's specs. Great for spotting issues or finding compatible upgrades. Download the latest version free.