UI Movement - The best UI design inspiration, daily
Red Pen - Red Pen lets you upload your design, share a short URL, and get live, annotated feedback super-fast.
Design Hunt - Curated design inspiration for everyone
Invision - Prototyping and collaboration for design teams
UI Jar - Hand-picked design inspiration for your real life projects
FLTDSGN - Daily showcase of the best flat UI design websites and apps