These are a variety of libraries used in the various bundled polyPod Features we've developed. If you're in the process of building your own Feature, you might find some of these useful.
The following utilities are all used in production by multiple existing Features, and are reasonably well documented:
A library used to parse and pre-process raw data.
A library used to analyse and enrich data.
A visual component library for polyPod Features.
A simple i18n library.
Utilities not listed above aren't widely (if at all) used or sufficiently documented yet. You probably want to stay away from them :)