A typeface built to simulate placeholder text in wireframes.
prototyping
Flow
Indigo Studio
An interaction design tool that helps you “create functional, animated UI prototypes while maintaining the focus on user experience at every step”
Framer
“a modern prototyping tool. It can help you to quickly build and test complex interactions and rich animations for both desktop and mobile.”
iPhone 5 PSDs
A nice collection including PSDs that can be printed for sketching as well as vector versions for high fidelity design.
Foundation
“An easy to use, powerful, and flexible framework for building prototypes and production code on any kind of device.”