I think, you (programmer who programming powdertoy) can make micro processors, where user can create system (by code or drag&drop logic gates) with specified number of inputs and outputs.
First of all, real logic gates only have two or one inputs and one output (please correct me if I'm wrong). Second of all, there is no need to have more than two inputs because of the associative property (p^q^r=(p^q)^r). Third of all, I made this .