Mobbin - Latest mobile design patterns & elements library
UserTesting.com - Usability testing has never been easier. Get videos of real people speaking their thoughts as they use websites, mobile apps, prototypes and more!
pttrns - iPhone and iPad user interface patterns
Userbrain - Easy, fast, and affordable user testing for websites and prototypes.
Page Flows - User flow design inspiration for mobile & desktop
userinput.io - Get on-demand feedback for your app, website or idea. Learn how to improve by hearing real opinions.