$ cat /etc/network/interfaces
# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)

# The loopback interface
# automatically added when upgrading
auto lo wlan0
iface lo inet loopback

iface wlan0 inet manual
        wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

iface home_net inet dhcp
iface work inet dhcp
iface some_wep128 inet dhcp
iface default inet dhcp

iface eth0 inet dhcp

# sed "s/psk\\=.*/psk\\=XXX/;s/psk\\=.*/psk\"\\=\"XXX\"/;s/key.\\=.*/key0\\=XXX/" \
       /etc/wpa_supplicant/wpa_supplicant.conf
network={
        priority=15
        ssid="at_home"
        id_str="home_net"
        proto=WPA2
        #psk="XXX"
        psk=XXX
}

network={
        priority=10
        ssid="work_net"
        id_str="work"
        proto=WPA2
        #psk="XXX"
        psk=XXX
}

network={
        priority=5
        ssid="hackme"
        id_str="some_wep128"
        key_mgmt=NONE
        wep_key0=XXX
        wep_tx_keyidx=0
}

network={
        priority=1
        ssid=""
        key_mgmt=NONE
}