Being a sysadmin by profession top is one of the command that i use most of the time when i face some issues. Now its a great tool, no denying that, but for my laptop which has colorful themes, icons, wdigets, even the terminal, it seems a bit out of league. So i use htop. Its same as top but provides things in more readable way by making things colorful and acii graphs of ram, processor and swap usage. You can install it by
apt-get install htop
aptitude install htop
For details, check it man page.