For those wanting a generator powered light here are a number of circuits for LED headlights. I am not sure of the claimed Lumens outputs as few people have access to an accurate Lumens test setup.

http://pilom.com/BicycleElectronics/DynamoCircuits.htm

It ought to be possible to retrofit the electronics and LED into older light shells or the cheap reproductions of older designs I have seen offered for sale.