routes.rb

link_to を簡潔に書ける
REST

ActionController::Routing::Routes.draw do |map|
  map.resources :projects
  map.task_archive 'tasks/:year/:month', :controller => 'tasks', :action => 'archive'
  map.home '', :controller => 'projects", :action => 'index'
end

<%= home_path %>
↓
/

<%= task_archive_path(:year=>2007, :month=>:5) %>
↓
/tasks/2007/5

<%= link_to "New Project", new_project_path %>
↓
＜a href="http://localhost:3000/projects/new">