This is mainly a list for myself and does not aspire to be complete or a reference to anybody other than myself.
- Solarized (for color)
- Le Corbusier’s Polychromie Architecturale (for color)
- iOS 7 colors (for color)
- Apple Human Interface Guidelines (for color and type)
- Firefox Photon (for color and type)
- Carbon (IBM) (for color and type)
- Material Design (for color and type)
- Adobe Color CC (a glorified color picker)
PS: I also maintain a list of decent free sans-serif fonts for use in webdesign.