Some useful resource usage monitoring tools for Linux

ps -- of course (especially with 'fuax' options ... pipe to 'less')

psgrep -- filter output of process summary

top -- Can be run with commandline

htop -- Very handy

atop -- Active and cumulative resource monitoring
cnt -- Kernel patch req'd to get full function out of atop. Anyone know more details on this?

nethogs -- shows the top gobblers of network bandwitdh :)

iptraf - ANSI-colored text interactive IP traffic summary and monitoring tool

Also: netstat, mrtg, iftop, tcpdump, wireshark, netstat -anp --inet, http://www.ubuntugeek.com/bandwidth-monitoring-tools-for-linux.html, SystemTap, http://ettercap.sourceforge.net/, http://members.optushome.com.au/emikulic/net/darkstat/, http://ex-parrot.com/~pdw/iftop/, http://gael.roualland.free.fr/ifstat/, ...