This is from the activo-rails gem

file.rb

module Activo
  module Rails
    module Helper

      # Displays a breadcrumb trail
      # 
      # options - A hash of attributes to apply to the wrapping div tag
      # 
      # Example:
      #   <div class="block">
      #     <div class="content">
      #       <h2><%= @news_item.title %></h2>
      #       <p><%= @news_item.content %></p>
      #     </div>
      #     <%= breadcrumbs do |b|
      #       b.item "Home", root_path
      #       b.item "News", news_path
      #       b.item "Awesome New Things", news_path(@news_item), :active => true
      #     %>
      #   </div>
      # 
      # Returns the breadcrumb trail.
      def breadcrumbs(options = {})
        items = NavigationBuilder.new
        yield items if block_given?
        
        options[:class] ||= "".html_safe
        options[:class] << " breadcrumb".html_safe
        options[:class].strip!
        
        content_tag("div", options) do
          content_tag("ul") do
            items.collect { |item|
              content_tag("li", :class => item[:class]) do
                if item[:active]
                  item[:label]
                else
                  link_to(item[:label], item[:href])
                end
              end
            }.join("").html_safe
          end
        end
      end
      
      # Assists in the creation of navigation menus
      class NavigationBuilder
        attr_reader :item_list
        include Enumerable
        
        def initialize
          @item_list = []
        end
        
        def each(&blk)
          item_list.each(&blk)
        end

        def item(label, path, options = {})
          options[:class] ||= ""
          options[:class] << " first" if item_list.empty?
          options[:class] << " active" if options[:active]
                  
          options[:link_options] ||= {}
          options[:link_options].merge!(:method => options[:method]) if options[:method]
          
          item_list << {
            :label => label,
            :href => path,
            :class => options[:class].strip,
            :link_options => options[:link_options],
            :icon => options[:icon],
            :active => !!options[:active]
          }
        end
      end
    end
  end
end