This is how Facebook built much of Paper. Matas and other designers used Origami to create unusually complete prototypes, and then a group of software engineers reproduced and refined these prototypes, building software they could ship to a world of phones. […]
Tweaks is a bit like Origami. But rather than providing a way of quickly molding prototypes, it lets engineers instantly shape and reshape an application after they’ve actually built it with software code. Both designers and engineers can test changes to an app without having to recode and recompile it. Instead, they can open a menu that lets them adjust all sorts of specific behavior, including the way the app’s smorgasbord of interactive animations responds to movements and finger gestures.
These are some pretty interesting tools.