Think of acts_as_tree + acts_as_list, but doing what you want: root categories, subcategories, positions, individual inherited permissions (and pretty view helpers).
A Plugin to add "Follow" functionality for models
Data collection for Airbnb listings.
A game with ants.
Autonomous Planetary Research Individual 50 is a exploration game set on a planet in a nearby solar system.
Synchronises Assets between Rails and S3
Babel is a set of simple internationalisation tools for LÖVE 2D.
Easily use backbone.js with rails 3.1
Human friendly unit testing for C++11
A fun game written in MacRuby. Send your bees out into the garden to collect honey and pollinate the flowers
Node.js body parsing middleware
An adventure story
Scientific / Simple calculator (iPhone clone)
Essay style documentation for Capistrano
Clever Ruby library
A clock on a blinkofant panel
CruiseControl for Ruby. Keep it simple.
Raspberry Pi Based Energy Monitor
a sudoku game with endless boards
a small book-keeping application in German
A better (for me) RSS aggregator. Collects numerous RSS feeds and displays entries in chronological order. Similar to the "planet" concept.
Scoreoid is a 'non-restrictive, reliable and easy to use server platform for game developers' and GGScoreoid makes it easy to use in the Corona SDK.
GGSound allows for easy management of sound effects and global volume in your Corona SDK powered apps.
Google Auth Library for Ruby
extends geokit and gives convenient helpers for adding google maps to your applicaiton