There's a law in the Netherlands that says cyclists must use lights when they ride at night. White in the front, red in the back. A lot of people have lights on their bike, but those get stolen frequently - my solution is to keep little lights pinned to the bag I always carry. As long as I go out with the same bag every time (which I do about 90% of the time), I always remember my lights.
The other day I actually got stopped on the way home for a bike-light check! Ok, my lights are pretty small, but they follow the rules, so I was good to go. A few other people weren't so lucky and the police were writing tickets.
It reminded me of one of my favorite Dutch TV commercials - a public service announcement that I first saw on Amsterdamize.com: