AutoTags, an open source project, is a plugin for RubyOnRails applications to automatically generate the relevant tags for the provided content. Its quite simple to use and provide easy integration with ActiveRecord. The plugin is very useful for social applications, community websites and all those networking applications where there is a scope of user generate content to be tagged. No more heck for the admin to sit and add the tags to the content or waiting for the users to add the tags to their content.

For installation and usage read here.

If you liked the plugin then please recommend me on workingwithrails.