Here is an update.
I've built 2 prototype interface boards.
The one on the left is a prototype for an all electric roaster (Alpenrost) and has controls for 12 V damper, 12 V drive motor, 110 V AC heater and fan. It's currently set up for 1 thermocouple, but there is room to squeeze one more driver in the middle of the board.
The one in the center is a prototype for a simple gas roaster (sonofresco) and has controls for 110 V fan, and burner on/off control. It has 2 thermocouple drivers (although there is no chip in one of the sockets yet).
On the right is the Arduino.
The proto boards are 2" x 3", so you can see how small the Arduino really is.
I'm missing one part for the Alpenrost controler... so It will be at least another day before I get it hooked up and ready to test.