The Velogical rim dynamo looks fun but it's only 1.5W.
IIRC the nominal output is 1.5W, but they do a couple of different versions (sport, special, touring) that produce more or less power at real-world speeds; I think they've been successfully used on the TCR &c.
@Thrustvector started
London Fixed Gear and Single-Speed is a community of fixed gear and single-speed cyclists.
The Velogical rim dynamo looks fun but it's only 1.5W.