Visualize Rails schema.rb with tool/plugin/script

Check out RailRoad.

It creates diagrams for models and controllers. I bet it will do what you want. It produces DOT files which can be viewed with Graphviz or other programs.

I've had some success with it, but when you have a ton of models, you may need to do some manual rearrangement to get a decent looking diagram.

_{(source: rubyforge.org)}

Checkout RailRoady for a Rails 3 project. It's forked from RailRoad.

https://github.com/preston/railroady