BIS (Blender Interplanety Storage) - is the online library of materials/shaders for the 3D creation "Blender". Through the BIS add-on, materials from the library can be downloaded and used directly in Blender. BIS provides access to many great materials under the Creative Commons license.
BIS is free for use and open source.

BIS website: https://bis.interplanety.org/

BIS is available both for Blender 2.8 and for Blender 2.7

There are more than 500 public materials in the BIS library.

Some development plans:

fill the BIS with more content
the searching system by categories
storing textures on the BIS server
different previews for solid, fabric, fluid
multi images previews
make previews faster (with server power)
improve interface in Blender (custom node groups with BIS info, custom selection window with more info and capabilities)
upgrade meshes storage - improve meshes saving (add vertex groups, creased edges, etc)
upgrade meshes storage - enable saving more objects types (particles, armature, curves, etc)
add third-party render engines to the BIS (lux, octane)
add math/meshes node engines to the BIS (Animation nodes, Sverchok)
integration into other 3d-programs with node systems (unity, ae, substance)
selecting different license types for meshes and node groups

Patrons only posts:
I will try to post some of my experiments with procedural materials.
The sample of the closed patrons post: pixelating texture