I recently got a Bell Muni helmet which has a visor built to have a Blackburn Flea headlight clipped on and has a place for the Flea taillight on the back. Ordinarily the first thing I do with a helmet is toss the visor, but this intrigued me, so I picked up a set of Fleas to give them a try. So far, I'm liking it a lot.
The Flea headlight puts out 40 lumens, which seems fine for a helmet light complemented by my 600 lumen light cannon on the handlebars. At full power it only lasts about an hour, but my ride is only 45 minutes, so that's OK with me. The rear light is reasonably bright, but I'm still using a PDW Radbot 1000 on the bike's rack. The taillight lasts around 10 hours on solid before it needs charged. These two lights together weigh about as much as my non-winter gloves and both are USB rechargeable.
(Image from
Cycling News.)