These are the signals used on the FNRttC (click on the pic to make it bigger).
For those of you intent on blinding rabbits the Magicshine range is, we are told, brighter than a car light. Magicshines cost from about £80 up, and suffer by comparison with the others because the batteries only give you three hours on full beam. You can save a few bob by importing direct from China, but you'd probably be stuffed if you felt the need to return it. The clip to the handlebars might take a bit of work.
the UK distributors currently have some special offers.
and, finally, if you can find one of these you've got yourself a bargain....From time to time front lights with 3w Cree emitters turn up. This one, from 7dayshop, is about £6 It's well able to light your way, but you'll need to carry spare batteries. Not all of 7dayshop's stuff is good, though - one of their back lights fell apart before it got out the front door