Atop is an ASCII full-screen performance monitor that is capable of reporting 
the activity of all processes (even if processes have finished during the 
interval), daily logging of system and process activity for long-term analysis,
highlighting overloaded system resources by using colors, etc.
At regular intervals, it shows system-level activity related to the CPU, memory,
swap, disks, and network layers, and for every active process it shows the CPU 
utilization, the memory growth, priority, username, state, and exit code.

WWW: http://openfacts2.berlios.de/wikien/index.php/BerliosProject:Atop-freebsd