LAN Data Interface

I have a selection of broadband modems,from previous IPs,before discarding them,is there anything else they could be used for? they have a very interesting population of components,that I feel could be usefull.Maybe some kind of Interface for transmitting TX+ & TX- DATA? Ive been looking at
Marcin's Toyota mp3 project on the softservice web site,his layouts look very impressive.He has created circuits to transmit data from the Missibushi HU to enable mp3 playback.