It sort of depends on what you're asking for.
If it's around the business model, the easy answer is to point them to a book like http://www.amazon.com/The-Lean-Startup-Entrepreneurs-Continu... There are great techniques in there for how to do customer development -- at this point it seems like required reading for business/product folks.
If you're looking for more mockups, something like Balsamiq is a good starting point.
Is there something else you're looking for?