Deer Departed

Deer-Departed.com is a good place to go for information on a variety of mechanical deterrents and chemical repellants.

I especially liked their page on deer alert velocity whistles designed to spook deer away from jumping out in front of your vehicle. It's nice to see all the people commenting on personal experiences. I installed a set on a Toyota station wagon, and once observed a deer pause at the corner of the road as if he may have heard the whistle. It's very hard to say. I never had a deer collision with the whistles while driving through some heavy populations in rural Ohio.