Get list of 'Friendly interface names' on a Mac (Airport, Ethernet, etc)
networksetup -listallnetworkservices will give you just the names (with an asterisk before disabled ports, in case you want to leave them out). networksetup -listnetworkserviceorder gives some additional info, like what /dev entry (en0, etc) they correspond to. Check the man page for networksetup for even lots more options...