Petzl DuoBelt LED 5
Price Paid: £50
A bit like carrying a floodlight attached to a brick. Heavy, but if you need to power then this is hard to beat.
I have the older model that has the halogen light, but has a low power bulb rather than the LED option. The halogen beam is very bright and will illuminate anything for almost as far as you can see. On low power mode the battery life is much extended, but you get much less light. the down side of this product is as I mentioned, it weighs a tonne.
The folks at Petzl have tried to help by putting the batteries ona belt pack and certainly this makes the headset very comfy to use. If you're out all night then this is not a problem, however you won't want to carry this baby during the day just on the off chance that you might need it if you get caught out. I'd carry my Petzl Zipka for emergencies and the Duo for those night time expeditions.