Velogical is, as far as I know, the latest and greatest

Their 3-phase generator is meant to power the forumslader USB charger. It delivers more power than a hub generator at speeds above 12 kms or so (the pink line is the output of a SON hub dynamo; the green line is the output realized by the 3-phase velogical).

Expensive as the generator + charger will cost more than $400 USD.

I do not have this -- both the 3-phase and the proper version of the charger have been released last summer, and by then I had committed to a hub solution. But will most likely try it next year.