Recently on the ror-talk mailing list there was a question on navigational menus, which revealed some interesting resources.

link_to_unless_current helper
Goldberg, Integrated Site Design for RoR
NavTab Plugin”

The navtab plugin, which is part of SeeSaw toolbox, is a neat little plugin, which provides instant support for tabs in your web applications. We will definitely be using this on our next RoR application.