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!

Mobbin - Latest mobile design patterns & elements library

Userbrain - Easy, fast, and affordable user testing for websites and prototypes.

pttrns - iPhone and iPad user interface patterns

userinput.io - Get on-demand feedback for your app, website or idea. Learn how to improve by hearing real opinions.

Page Flows - User flow design inspiration for mobile & desktop