I use an old backpacking headlamp for a front (white) flasher. I had to fabricate a mount (to fork brake hole) from some flat nickel stock. The head lamp is a Princeton Tec EOS I retired from backpacking for a new. improved headlamp. The EOS has a wide, floody beam and flashes at about ~4 hz.

I see they now sell this with a bike mount:

http://www.princetontec.com/?q=eos-bike