Brings to mind an earlier design of mine, dubbed Digituino,
designed to Drive higher voltage (12V) Common Anode 7-Segment Displays, using TPIC6B595 shiftout registers (150mA per IO, up to 50V), with RS232, SD card socket, ATMega328P
Didn't bother with shield compatibility with shift registers, RS232 adapter, and SD card socket and 3.3V buffer built onto the card.
Pretty hefty feel with all the connectors.http://www.crossroadsfencing.com/BobuinoRev17/
Bare boards available if any one is intersted. The SD socket is SMD, with pretty widely spaced pins that are easy to solder.