Salt includes a number of built-in external pillars, listed at Full list of builtin pillar modules.
You may also wish to look at the standard pillar documentation, at Pillar Configuration
The source for the built-in Salt pillars can be found here: https://github.com/saltstack/salt/blob/develop/salt/pillar
Docs for previous releases are available on readthedocs.org.
Latest Salt release: 2015.8.10