Heathrow Airport has launched new maps of their terminals at Heathrow which show the layout of Terminal 2 especially well. (Download a .pdf version here.)

Showing the drop off area:

The main departure lounge shows the location of all the main shops, including the Lufthansa and Aer Lingus lounges. (Green for food outlets, Purple for shops/retail)

And interestingly the arrivals maps shows the locations of what I assume is the new United Arrivals Facility and a paid (?) Plaza Premium Lounge.