Lin He's repositories
acts_as_category
Think of acts_as_tree + acts_as_list, but doing what you want: root categories, subcategories, positions, individual inherited permissions and some script.aculo.us view helpers.
acts_as_rateable
Acts_as_rateable is a Ruby on Rails plugin which makes ActiveRecord models rateable through a polymorphic association and optionally logs which user rated which object. This plugin is used in production and Rails 3 compatible.
acts_as_recommendable
Collaborative Filtering for Rails
cache-money
A Write-Through Cacheing Library for ActiveRecord
emacs-rails-reloaded
Minor mode for editing RubyOnRails code in Emacs
geokit-rails
Official Geokit plugin for Rails/ActiveRecord. Provides location-based goodness for your Rails app. Requires the Geokit gem.
permalink_fu
ActiveRecord plugin for automatically converting fields to permalinks.