** UPDATE: You can get these boards at tindie.com in the DTronixs store
I meant to post this a few weeks back but holidays etc. got in the way, so here it is now.
So here we have a simple two relay DPCO board. Either of the relays can be selected from 8 off the GPIO pins from the Raspberry Pi expansion header.
Circuit schematic is here
and here it is on a Raspberry Pi