Mapping a network

"G|_|Y |\\/|AC0|\\|" <[email protected]> Tue, 16 May 2006 13:52:48 -0700
Newsgroups gmane.mail.spam.spamcop.geeks
Organization http://216.73.122.76/
Message-ID <[email protected]>
I just inherited IT as a part-time addition to my engineering duties.  I am 
making an
inventory of hardware and software, what server is at what IP address, etc. 
Does
anyone have any favorite tools for doing an automated discovery of what is 
on a LAN?