In the process of kiting myself up to go underground I've come across a couple of items that might be of interest to some of you who might like to adapt items for other uses. This site
http://www.ultraleds.co.uk/ has a conversion LED kit for the Maglite 4D, its very expensive at £75 but it comes with the pcb, aluminum heat sink and glass lenses, which fit into the head of the Maglite. Could be used as a very good standby light or pointer.
The other item is a 12v MR16 (otherwise known as dichroics) This version sports 3, 1w Seoul P4 LEDs It has its own inbuilt voltage regulator and will accept AC/DC from 8 to 15 volts. The light emitted is awesome. I've had it connected to a 11.1volt Li-Po. It's rated at 270 lumens which is apparently the equivalent to 40 watts. Weighs in at £20. Obviously its not waterproof and because of the configuration might be hard to adapt for general underground use. But it could be used for communal/survey UG or for camping/social.
BTW I'm not advocating the use of Li-Po's for UG use they are a little unstable/dangerous. They would have to be protected from any form of damage and over discharge. Better to use Li-ion or Nicads.