Freebiesbug - Collection of the best free web design resources.
Makerbook - A directory of the best free resources for creatives
UI Movement - The best UI design inspiration, daily
Nawvel - Nawvel is a handy-dandy library of tried, tested & curated resources.
Freepik - More than a million free vectors, PSD, photos and free icons. Exclusive freebies and all graphic resources that you need for your projects
The Starter Kit - Curated resources for web developers and visual designers