You could try taping a tirefly to the top of your flag pole. The only problem I had with this was it would only light up if I went over a bump. If you could figure out a way to make it stay on you would be all set.

I also thought it would be cool to get a rigid small diameter clear plastic tube and run fiber optic cable up it with some sort of light source at the bottom. Then attach a flag to the top. That way you have a shaft of light waving behind you to get peoples attention at night.

Andy