Emacs as a Ruby On Rails IDE

Currently I'm using some old version of Rinari with minor modes for different formats - haml, yaml, js, etc.
I am about to rebuild from scratch my Emacs configuration, start with Emacs 24 and create a custom RoR support or find a suitable one.
The post will be a placeholder for features I would like to have for RoR development.

Features

Modes

The following modes/languages support:

• ruby, inline ruby, inline rails console
• erb
• haml, sass, scss
• html, css
• javascript, javascript minor in html | erb | haml
• yaml
• shell
• RSpec, Cucumber

Navigation

 Jumping

• Jump any-to-any - model, controller, views, specs
• Jump any-to-any namespace support, method name support
• Jump to definition project coded
• Jump to definition RoR and gems sources
• Jump inside source file
• Fuzzy jump (like ido works 'usrsn' should show UserSession as a jump option)

Help

• attach help on rails, gems and ruby libraries

Packages

• el-get
• elpa