SysGauge - SysGuage is a responsive software utility that monitors the memory status, CPU usage, as well as network and disk activities of your system.
htop - htop - an interactive process viewer for Unix. This is htop, an interactive process viewer for Unix systems. It is a text-mode application (for console or X terminals) and requires ncurses. Latest release: htop 2.
Big Meter Pro - Big Meter Pro is a utility that monitors the disk and memory of your CPU.
glances system monitoring - Glances is a cross-platform system monitoring tool written in Python. Written in Python, Glances will run on almost any plaftorm : GNU/Linux, FreeBSD, OS X and Windows.
Process Lasso - Process Lasso is NOT yet another task manager.
vtop - vtop is a graphical command-line tool that uses unicode braille to chart CPU and memory usage.