A micro-howto on how to make your network admin's life easier and send your hostname via DHCP - so that it shows up in your router's connected devices monitor.
sudo vi /etc/dhclient.conf
and add the following lines:
send host-name "<your hostname>";
send dhcp-client-identifier <your MAC address>;
hint.... HINT... HINT ;-)
Edit: In Ubuntu (and possibly also other Debian-based systems) the file to modify is not /etc/dhclient.conf but rather /etc/dhcp3/dhclient.conf .