Domains for sale ? (This is not spam...)

["James R. Fisher" <JFISHER () OMEGA7 WR USGS GOV>]

Greetings:
Does anyone know of a website on which domain names are offered
for sale ? This would be something of an underground enterprise
if it exists ?

I ask because it appears that a domain in which I have some interest
has apparently come up for sale (usgs.com). You can see this just
from the top of whois output for usgs.com .
Thanks.
-jrf