AJAX Tree Control is a modified version of SilverStripe's tree control. It adds dynamic loading of child nodes via AJAX. The default implementation uses the prototype library to make dynamic requests, but this behavior can be overridden by setting functions on the global Tree object. There are a few demo Ruby on Rails applications included in the distribution that show how to use and customize the tree.
The Atom Publishing Protocol framework for Ruby aims to simplify the implementation of Atom Publishing Protocol (APP) support in Web applications. It achieves this by implementing a framework that handles the protocol-level duties for the programmer, while not making any requirements for the site design.
BitNami Tracks Stack is an all-in-one cross-platform installer for Tracks, a Web-based application to help you implement David Allen's Getting Things Done methodology. It installs Tracks, Ruby On Rails, and everything else necessary to have a running program in minutes. It works on Windows, Linux, and OS X.
Compendium is a tool to generate encyclopedia-type Web sites (e.g., databases of books, authors, publishers, and literary genres) from content housed in a MySQL database, based on HTML templates. It generates pages with relatively static content and relies on Ruby on Rails for providing a backend to maintain the database. It radically separates content (in the database) from presentation. To facilitate this separation, it allows users to define their own custom tags and provides a simple translation engine to deal with, for example, tables of contents and navigation paths.
Devalot is a social networking application centered around software projects. It connects the user community with the development community and encourages participation and communication. It includes all the features you've come to expect in modern Web-based applications such as tagging, comments, and a wiki, as well as features you'd expect in project tracking software such as ticketing. It has features similar to some of those found in Trac, Collaboa, GForge, Mephisto, and Typo.