[K12OSN] memory issues

[Huck]

top - 11:34:14 up 23:45,  1 user,  load average: 6.18, 5.67, 3.73
Tasks: 323 total,   5 running, 318 sleeping,   0 stopped,   0 zombie
Cpu(s): 12.7% us,  6.4% sy,  0.1% ni, 76.9% id,  0.0% wa,  0.2% hi,  3.6% si
Mem:   4153708k total,  4094596k used,    59112k free,   479060k buffers
Swap:  2040244k total,        0k used,  2040244k free,  2787320k cached


1 user is a lie of course there are at least 12 people logged in...
I don't see any reason for this much memory to be getting sucked up 
though...they are all running firefox AND/OR openoffice writer.

any ideas? I remember seeing a long while ago some cmd-line tool to 
track memory usage ever-so-often...I've searched the archives and 
google'd without luck finding it. anyone remember? thought it was like 
"memd" or something

--Huck