Roles UI is a graphic interface library for Ruby on Rails which provides the ability to manage roles and permissions in realtime for applications which use Cancan. It is a Rails engine, so it has its own namespace. You can reach Roles UI in /roles_ui. Roles UI consist of two main entities, Role and Permission. Each Role may have a permission set. Roles belongs to users. Roles UI extends your User model so you don't need to create this association. By default, Roles UI is configured to work with the User model.
XapianFu is a Ruby library for working with Xapian databases. It builds on the GPL licensed Xapian Ruby bindings, but provides an interface more in-line with "The Ruby Way"(tm) and is considerably easier to use. For example, you can work almost entirely with Hash objects, and XapianFu will handle converting the Hash keys into Xapian term prefixes when indexing and when parsing queries. It also handles storing and retrieving hash entries as Xapian::Document values. XapianFu basically gives you a persistent Hash with full text indexing (and ACID transactions).
libcraigscrape is an easy library to do the heavy lifting between you and Craigslist's posting database. Given a URL, libcraigscrape will follow links, scrape fields, and deduce Ruby objects out of the raw HTML from Craigslist's servers. libcraigscrape was primarily developed to support the included craigwatch script.