Howdy...
I love the idea of an expansion card.
My personal preference is an SD card rather than Compact Flash, but I guess the Compact Flash cards are pretty cheap as well.
Some kind of sound chip would be nice to get some noise out of the board...
What about I2C, would that be a possibility ?
I'm trying to get a Micro controller mapped to $7F00 (XCS0B) and $7F20 (XCS1B) to get VGA and Sound.
It works most of the time but it's not stable, I'm thinking I need to come up with something else like SPI or Serial.
Keep us updated...