See http://dima-exe.ru/rails-on-emacs or page in rubyforge http://rubyforge.org/projects/emacs-rails/

Dmitry Galinsky just released a rails minor mode that ties many features into one location:

Features:
* Identation
* Code highlight
* Non-intellectual autocomplete
* Class/methods navigation
* Management of WEBrick/Mongrel
* Display color log file
* Toggle Switch between Action/View and other file (tests, helpers) automatically or with menu
* Switching to file from current line f.e. from redirect_to :controller => "foo", :action => "bar", swtiches to this controller/action
* TextMate-like snippets (snippets.el)
* ERb refactoring (create partial from selection, create helper from block)
* Automatic TAGS generation in RAILS_ROOT directory
* Quick access to the main configuration files
* Documentation search using ri or chm file and Rails API reference in HTML
* Quick start svn-status in RAILS_ROOT
* Integration with script/generate script/destroy (controller, model, scaffold, migration)
* Goto menus for quick access to controllers, models, and other.
* Auto-determination of current rails DB settings and running SQL console
* Automatic opening of browser on current action (from view or controller)
* Debug integration with firefox/ie
* Integration with interactive scripts script/console and script/breakpointer
* Fast navigation in Rails root hierarchy 
* Fast running of rails rake with autocomplete
* Integration with tests