The EyeTV netstream is an old-ish but well designed device which takes in a TV coax connection and spits out MPEG2 streams over the network.
The Reg reviewed here: http://www.theregister.co.uk/2010/04/05/review_peripherals_elgato_netstream_dtt/
It’s a nice device which adheres to the UNIX philosophy of doing one thing well. Apparently it also only draws 6 watts of power.
To set up you need access to an OSX or Windows box on which to install the EyeTV software, which sets up the device (scans for frequencies etc).
I had lost my serial, so following this chap’s http://www.youtube.com/watch?v=1gnfSE4XimA instructions I modified /etc/hosts, removed any plist data.
127.0.0.1 services.elgato.com 127.0.0.1 updates.elgato.com 127.0.0.1 services.eyetv.com
sudo rm -i /Users/Shared/Library/Preferences/com.elgato*
and then downloaded Elgato.EyeTV.v3.5.3.MAC.OSX-HOTiSO from a well-known source of pirate software, which thankfully came with a serial.