Like as there was: Practical Tcpdump examples?
I want to gather good nmap examples that can be usefull!
Like as there was: Practical Tcpdump examples?
I want to gather good nmap examples that can be usefull!

Secrets of Network Cartography:
A Comprehensive Guide to nmap
Written by James Messer
Is quite a good reference in itself.
It is available as PDF and on-line reference.
There are a few cheetsheets too,
SBDTools has Nmap5 Cheetsheet v1 (pdf), among other things.
And, don't forget the 'nmap' tag right here and across SE sites.
Simply finding out what systems are up on your local net:
nmap -sn "192.168.0.*"
Use it sometimes to find out if a machine that I can't access locally (something has crashed, graphics driver errors, etc.) is available via SSH.
I also use it occasionally just to query what services I'm running. If I've found that I have enabled a service (such as vsftpd) and forgot to disable it after use, I can stop it.
See man nmap for other ideas.