We're going to pick up the pieces, and build a Lego IP data-transfer network out of a train set, courtesy of Hackaday.com.
Possibly one of the slowest speed rates out there; but also the most charming. Hacker Maximillien has devised a system that utilises a USB flash drive, to carry data around to different nodes (we'll call them stations) on the rail. The four nodes consist of aluminium foil contacts, which establish the connection from the attached computer to the USB storage on-board the train. After the data is sent across, the drive is unmounted and the power flow is transferred to the train to propel it forwards to it's next requested destination.
Because of the...well...physical form of data transportation, do not expect anything near zero-latency; but with it being over USB, the bandwidth is going to be strong.
While some may call it rather pointless, we can see it making for a pretty good illustration of the ins-and-outs of networking for educational purposes. Either way, we can't help but find this quite the charming piece of technology, quite like The Little Printer.