After a near-miss accident in downtown Minneapolis on September 9, I have been more consistent in using lights in dim conditions. I don't know if it would have prevented the mashing I almost received on 9th Street, but it certainly would not have hurt my odds (on a side-note, I've also been wearing my dorky yellow PDRMO* vest as well).
After some research and hand-wringing, I sprung for a set of Nite Rider dual lights about two months ago. Yes, the Nite Riders are expensive, but the sting of that was offset somewhat by a coupon I earned via Do.Cycle miles that I racked up by commuting on my bike (I am also down a shirt size, too).
The Nite Riders are great - they attach in less than a minute, fit all my bikes, and they are very bright. They have a day-visible flash mode that I have been using on early morning commutes and in rain/gloom. I think the flashers really make a difference; I have noticed fewer cars turning in front of me (I think) and it's obvious that I get more attention from pedestrians, which I think correlates to more attention from drivers as well. It's also a lot of fun to zoom around the IDS Center parking ramp with the strobe blazing away; it scares the shit out of the lawyers shuffling to the elevators.
On the rear end, I am running a Super Flash. This seems to be way better than this POS that keeps falling off my bag and smashing on the ground - it's a miracle that blinky still works, but it does, so I still have it laying around somewhere.
My ultimate favorite flasher is the "UFO". It's made by a company called Filzer. The UFO is a tiny (but bright) LED flasher that clips onto a messenger bag, under-the-seat bag, or even a zipper pull. It's got a "rotating" setting, a flash setting and a steady setting. The thing is essentially weightless and is only about an inch long, but it's very effective. The clip is well-designed and because it weighs so little, it never bounces off the bag. The things only cost something like $12 (CDN), too.
Testimonial: I was riding back from MMRB on Prior Ave. in St. Paul at about 9:00 PM earlier this summer. A couple in a car pulled up beside me while I was waiting for a stop light. The passenger in the car rolled down her window and told me how great the light was ("We saw you from two blocks away! Where can I get one of those!?"). I told her that sadly, the only place I have ever found these was in Canada. I found mine (both a white and red one) at Mountain Equipment Co-op in Calgary. I wish-wish-wish a good local bike shop would start carrying these units.
It's getting noticeable darker, so I expect I'll be using these more and more in the coming weeks (and hopefully months). And I hope they work for me.
* Please Don't Run Me Over