How to call a method in a controller with link_to?

Hello everyone, I have a MessagesController created with rails g
scaffold and the user may create messages that get saved, in tihs
controller I have a method called 'tweet' that (using the twitter
gem / Twitter API) triggers the given message to twitter. However I
don't know how to put a tweet link in my /tweets/index.html.erb... you
know this link won't be calling an action (edit, destroy, new), this
link will be calling a method created by myself in the controller. Can
you help me?

P.S: I am using rails 3.

Thanks!

Rodrigo Alves Vieira

routes.rb

resources :messages do
  member do
    get :tweet
  end
end

should give you a tweet_message_path to use in a view like

<%= link_to('Tweet This', tweet_message_path(message.id)) %>

and direct the app to your tweet method in the messages_controller