MediaKits - The easiest way to create a media kit
Interfacer - Collection of more than 200+ free design resources
Frontify Workspace - The overall tool for creative & design collaboration: - upload, manage & share assets
Facebook Design Resources - A collection of free resources made by designers at Facebook
Styleguide - A tool to make creating and maintaining styleguides easy
Freebiesbug - Collection of the best free web design resources.