Dynamo driven:
HOMEMADE light, there is on other possibility. Ideally with three individual led
high budget:
Lupine Tesla
"higher" budget and builder:
Lupine Tesla head + homemade Li-Ion pack
budget and heavy builder:
any 3-/ 4-Led or MC-E or P7 light from Dealextreme or Kaidomain, or ..., used just the head and with homemade Li-Ion batt pack.
If ever something of the cheap components fails: remove it with a good one (refers to driver or led or soldering)
budget and starting builder and flashlight user / backpacker:
any good actual led light (means Fenix, Jetbeam, ...) with the battery setup You like + homemade light holder for bars
example:
budget:
Sigma Powerled black, or
Sigma Karma
feeling to be the lucky guy:
same as budget, starting builder / backpacker but using a ceapo light from DX.
Maybe the one ordered survives
imho: the best and cheapest is homemade with using an existing flashlights head,
the most useful is starting builder + backpacker, because one gets a light that is enough for trail riding and also has a nice flashlight for other things than biking.
That is my setup for nightrides (very rough or unknown terrain: add a headlamp)
With a spare set of batts, 4 hours of full power light. Still smaller and lighter than any other setup. Less bright than powered light (Tesla), but brighter than three-led w. dynamo.