Find out who's logged on command

This command is good for administrator to trace who user 's logged on to particular workstation especially the domain user.
This is only applicable on windows server.

Net session | find "\\"

By using sysinternal's ps tool, you may check the remote pc's logged on users.
Psexec \\server net session | find "\\"

Originated from http://www.robvanderwoude.com/ntadmincommands.php#Cmd01