Do you use multiple domain names and park them on your main domain to drive more traffic to your site? Does/will this work?

Mark

If the domain names themselves contain relevant keywords, they will definitely add SOME additional traffic. However there are more effective SEO techniques.

If the domains you forward already have an established traffic base, that of course will help even more.

Parking is a bit decrepit, why would you share your traffic with others if you have it?

I do this to protect the name mostly. But if the content is dynamic, I usually forward the domain - otherwise I just park it on top. Works well into getting SOME traffic, not too much. I've never done this for the traffic though.