I made a batch of EXP boards that plug into the bottom of a toaster NES. One of the headers on the board is pin compatible with the Famicom EXP port. You plug a 15-pin Famicom peripheral into a DB15M header cable which connects to the EXP board plugged in under the NES.
I'm still waiting on the 16-pin R/A header from Digikey, but here's what the board looks like...
http://www.chykn.com/ENIO-EXPBoard-v1_2-first.jpg
One problem - while I've verified that the signals are routed correctly, I don't have any FC peripherals. Is there anyone out there with a Family Basic keyboard (or another 15-pin FC peripheral) who could test this and maybe post a Youtube video for verification?