A list of those programs you only need once in a blue moon but can never remember the name of.

• lsof - list all file handles. Can be useful when a filesystem won't unmount.
• modinfo - describe module and arguments that can be provided
• htop - top on steroids
• atop - lists the most active processes based on CPU, memory, disk and network usage
• iotop - lists io usage of programs.
• duc - visualise disk usage

• iftop - lists network usage by ip address
• iptraf - similar to iftop but has a bit more functionality
• nethogs - per process network usage
• nload - per interface usage and console graph
• ntop - not what you're looking for