I think a lot of the other posters are correct. Diagrams of classes, interactions, event flows, dependencies, network architectures, and yes, even pseudo-code.

I think a lot of the other posters are correct. Diagrams of classes, interactions, event flows, dependencies, network architectures, and yes, even pseudo-code. Basically, if it is an idea, concept or design, draw it out. If it is functionally correct code that compiles, screen-cast and type it out.