helper.rb

  def nav_link_to(title, url, options={})
    li_options = {}

    if matches_options?(options)
      li_options[:class] = "active"
    end

    content_tag :li, li_options do
      link_to title, url
    end
  end
  
  def matches_options?(options={})
    url_matches?(options[:url]) ||
      path_matches?(options[:path]) ||
      controller_matches?(options[:controller], options[:action])
  end