I've posted patches to the net-snmp website so that you can compile your own snmpd. I think someone is preparing it for fink.
MRTG has been ported to Darwin- it used to be available from http://www.macosxsw.com, but it doesn't seem to be there now. I would suppose he put it in Fink...
OK, after DiskBreaker pointed out nvram and I confirmed that the Startup Disk is saved in the non-volatile RAM (via some technote, I don't remember which), I started playing...
/usr/sbin/nvram -p will list all the nvram variables
nvram -h (or any other invalid option) will list all the valid...