There's so many uses for the Parallax Propeller Proto Board that we've lost count. However, making this Twin Prop Board is one of our favorite projects and most useful.
The idea is to take one Parallax Propeller Proto Board and add a solderless breadboard and another Propeller chip. Wiring the prop takes place on the back of the board and a connector helps make the circuit connections. This is a good board for experimenting with multi-prop experiments and testing new communications code.