The Rails Authorization plugin allows you to easily control which features of your application can be used by each individual user or type of user. You can use this plugin for complex levels of authority and per-object roles, as well as simple administrator/user situations. For more information and example usage, click here.
Author: Bill Katz
Installation:
ruby script/plugin install git://github.com/technoweenie/restful-authentication.git
ruby script/plugin install git://github.com/DocSavage/rails-authorization-plugin.git