Turn on a host magically via the network :)

aptitude install ethtool

ethtool eth0

Settings for eth0:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 100Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: pumbg
        Wake-on: d
        Current message level: 0x00000001 (1)
        Link detected: yes

Here: disabled

“Supports Wake-on:” these modes are available.
“Wake-on:” what is actually configured

The different modes taken from “man ethtool”:

     p  Wake on phy activity
     u  Wake on unicast messages
     m  Wake on multicast messages
     b  Wake on broadcast messages
     a  Wake on ARP
     g  Wake on MagicPacket(tm)
     s  Enable SecureOn(tm) password for MagicPacket(tm)
     d  Disable (wake on nothing).  This option clears all previous options.

Install the needed sofware:

aptitude install wakeonlan

Make sure you have the MAC address of the network device you want to wake up.

Then kick the hosts ass:

wakeonlan XX:XX:XX:XX:XX:XX

That's it, your host should start up immediately.