I commute every day, morning ride is in darkness. I have a flamethrower dual headlamp and a backup headlight on the MB-Zip full-boat commuter bike, versus just a front and rear single-LED blinky on the stripped-down PSVN. But I feel equally noticeable and safe on the PSVN, due to my helmet light.

A fairly-directional and not-too-powerful helmet light is a great thing, because it is mounted up high, you can waggle it to get attention, and you can shine it straight into a driver's face to really get attention. I can always get a driver's attention with the last bit. This applies mostly to when you're approaching cars at intersections, driveways, etc - obviously if they're going to ambush you from behind, the helmet light doesn't help, you'd need a tail gunner. I have a red single-LED blinky on the back of my helmet for good measure.

My helmet light is a kludge made from a Petzl mountaineering headlamp, but there are bicycle specific helmet lights too. AA battery power is enough, you don't need power cords draped down your body.

The other thing is reflective material, which is basically free light. I'm not willing to stick reflective tape on my bike frame, but I put bits of it on the helmet, jacket, pedals, etc.