Rails UI widgets

Are there any popular plugins/gems for creating/generating rails UI elements such as navigation, progress bar, forms, tabular displays etc? Seems like I am doing that over and over again and differently each time? Let me clarify my question: while everyone is free to choose whatever they want for authentication, it seems like most people use Restful_authentication plugin. Similarly, are there any such popular plugins/gems for Rails driven UI? Thanks for your time. Bharat

Robert Walker wrote:

Read up on Rails 3.0 and I'll see what I'm getting at.

It supports reflection?