Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Interfacer - Collection of more than 200+ free design resources
Pocket - When you find something you want to view later, put it in Pocket.
Facebook Design Resources - A collection of free resources made by designers at Facebook
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
Freebiesbug - Collection of the best free web design resources.