... and transmit it over a short-distance RF link (<10ft) using something like one of the Nordic / MIRF transceivers, and then have a receiver which drives one of those displays with the data received over the RF link.
Half my work is done for me -- I found this design which is more than enough to do the receiver, using an Arduino: http://www.junksoup.com/address/address_schematic.pdf
I *think* they're using 5 GPIO lines to do something like SPI there -- it's transmit-only to the display. So, now I just need to do the same thing in reverse -- make something that has 5 input lines and multiplexes them into a bitstream for the RF chip. I understand how to do bit-banging serial output, but what's the best way to do bit-banging serial input? Would I need an ATMega-class chip to do that, or would one of the ATTiny series suffice?