Actually, I just read up on the E-WERK from the Busch & Mueller catalogue. From their catalogue: "At a speed of only 15 km/h, it charges as quickly as standard mains connected chargers." Since I'm riding on 29" wheels, I'll have to go a bit faster to get that much power output; on a long stretch of empty highway, I'll be going a whole lot faster.

Edit: Holy crap! That E-WERK thing is $250 on Amazon.ca! Maybe I can just plug my phone into a sack of potatoes.