calefaction/app/views/shared/_header.html.erb

<div id="header">
  <p>
    <%= link_to 'Home', controller: 'tools', action: 'index' %>
  </p>
  <p>
    Users:
    <%= link_to "Signup", controller: "users", action: "create" %>
    &bull;
    <%= link_to "Login", controller: "users", action: "login" %>
  </p>
  <p>
    Admin:
    <%= link_to "Admin", controller: "admin", action: "index" %>
  </p>
</div>