Put the link to the map key back.

app/views/layouts/site.rhtml

@@ -81,6 +81,7 @@
 	<%= link_to "Users' diaries", {:controller => 'diary_entry', :action => 'list', :display_name => nil} %><br />
         <a href="http://www.opengeodata.org/">News blog</a><br />
         <a href="http://wiki.openstreetmap.org/index.php/Merchandise">Shop</a><br />
+        <%= yield :left_menu %>
       </div>
 
       <%= yield :optionals %>

app/views/site/index.rhtml

@@ -1,3 +1,7 @@
+<% content_for :left_menu do %>
+<%= link_to "Map key", "http://wiki.openstreetmap.org/index.php/Map_Key" %>
+<% end %>
+
 <%= render :partial => 'search', :locals => { :onopen => "resizeMap();", :onclose => "resizeMap();" } %>
 
 <div id="map"></div>