mpvlib provides Ruby bindings to the MPV media player, via libmpv.

An album-based music catalog/player.

NewsFetcher monitors RSS and Atom feeds, tracking which items have been delivered, and sends new feed items as individual HTML emails using configurable mail delivery methods.

PhotoUtils provides Models, formulas, and utilties for photography optics, etc.

Polygon provides a framework with strong separation of concerns between clients, developers and web designers

Quadtone Toolkit (QTTK): Tools for working with the quadtone printing process.

Sexpr helps manipulating s-expressions in ruby.

A simple hierarchical configuration object.

Simple::FileDB is a database built upon JSON files.

SimpleServer provides a simple web server.

Yet another ruby backend framework, I'm afraid

Talktome helps you talk to users by email, messaging, sms, etc. It abstracts the messaging mechanisms and lets you manage message templates easily.

A thor extension for generating directory structures from file trees defined in YAML

WebChecker checks static websites for consistency.