How can I emulate a SO-style tagging system in Rails?

Question

I think that the SO-style tag system works very well and would like to emulate it in an app I am building with Rails. I am especially enamored by the way the tag entry box looks up the top 5 tag matches as you type. Is there a built-in function or plug-in that would do something similar for me in Rails? Otherwise, what would be a good way to go about building this functionality?

Answer 1

My favorite tagging rails plugin is http://github.com/giraffesoft/is_taggable/tree/master

To do the autocomplete, I'd probably use something like: http://blog.jackhq.com/posts/3-how-to-add-jquery-autocomplete-to-your-rails-forms-in-a-restful-way

It would be easy to extend is_taggable to do a counter_cache for each tag and then have a default scope on that counter_cache column.
Probably in this file.