Whowatch is a interactive, ncurses-based, process and users monitoring tool
which updates informations in real time.
It can be described as a some kind of interactive mix of ps, pstree, lsof,
w, finger and kill.
You can watch informations about users currently logged on to the machine:
login type - ie. "ssh" "telnet", tty, host, idle time and command line of 
their current process. You can also naviagate in processes tree, watch process 
details (memory, uid, open descriptors with TCP sockets mapped 
on IP:port -> IP:port pair etc.).
Whowatch has support for plugins.