A plugin/gem that provides access to the Prowl API (http://prowlapp.com). Works with Rails 2 or 3 as well as any other Ruby web frameworks or in your own scripts.

Runs regular Rails/ActiveRecord migrations via the Percona Toolkit pt-online-schema-change tool.

A Ruby wrapper around the DPS-hosted PxPay service

Logs exceptions inside a database table. Now available as gem for Rails3 (previously a plugin for Rails2)

Port of the old, venerable ActsAsTree with a bit of a twist

ActiveRecord-like associations for ActiveResource

Active Record caching and indexing in memcache.

Components allow you to call other actions for their rendered response while executing another action

This is a quick'n'dirty gem to parse Quicken QFX format.

RubiGen - Ruby Generator Framework

A simple to use, yet powerful Ruby framework for building console-based applications.

Data mining and machine learning algorithms for JRuby

This is a Ruby API for Fitbit.com, currently scraping, but soon will use the officail API (when released)

Call Lua from Ruby (and Ruby from Lua in Ruby)

ScheduleFu allows scheduling events with dates and times. It includes both the model and view portions of a calendar. It borrow heavily from acts_as_calendar (http://github.com/dball/acts_as_calendar) and calendar_helper (http://github.com/topfunky/calendar_helper).

Integrate SimpleCov results into Atlassian Bamboo CI server

Crops images based on entropy: leaving the most interesting part intact. Usefull for automatic cropping or resizing of images.

A library for using Notifo. Notifo is a way for users to receive mobile notifications for anything, more at http://notifo.com. This gem uses John Nunemaker's awesome HTTParty.

SocialPoster is a gem that allows you easily post to different social networks.

Spree Mail extends Spree by adding a mailing list subscriber model, sign up forms and an admin to send messages.