I don't understand why this isn't a higher priority for more commuters. A helmet is a safety device. There's nothing it can do to enhance safety more than decreasing your invisibility does.

I got a Bell Muni about a year and a half ago. It started out hi-viz yellow. Over the course of 18 months it's starting to fade to white, but it's still better than most helmets in this regard.

The Muni also has built-in rear flashers and convenient options for mounting front and rear Flea 2.0 lights, which have an amazing brightness-to-weight ratio. I hate the pads on the Muni (because they collect sweat and randomly dump it in my eyes), but the safety options are enough to make that tolerable.