I think Nmap is meant for networks.
"Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. It was designed to rapidly scan large networks, but works fine against single hosts."
Excerpt from:
http://nmap.org/The last part "...but works fine against single hosts." is somewhat confusing to me since i'm not sure this means it works on computers that are not in a network.
I'm curious to see some other opinions on this.