Local network service discovery

Avahi is a system which facilitates service discovery on
a local network -- this means that you can plug your laptop or
computer into a network and instantly be able to view other people who
you can chat with, find printers to print to or find files being
shared. This kind of technology is already found in MacOS X (branded
'Rendezvous', 'Bonjour' and sometimes 'ZeroConf') and is very
convenient.