Haha... I will say "mock up" from now on. Thanks! (My dragon would probably end up looking like a fire breathing cow anyway) Great advice about securing customers first. If you can't do that it's probably not worth either of your time.
I wasn't poking fun at your word choice, don't worry. I'm just sort of skeptical that product-related process documents actually add any value. Money? Customers? These are things I don't have enough of. Documents? Any idiot can write documents. Many do.
Checks, letters of intent from customers who they've sold the pre-extant system to +, customer lists, etc.
Sketches are nice, too. I prefer charcoal as a medium and dragons as a subject. A good sketch makes a great complement to a check or LOI.
+ Happens all the time. Really.