Mapping Your Objective
If you have done a map search for random companies lately, you'll start noticing a trend. Companies that aren't franchised and have only one physical address are popping up all over the place. If you do a search for Illinois Web Design, a few names... not mentioning them... will pop up across the entire map of the state, when they are located at only one address. This is a trick that is being used more and more for SEO and SEM. I won't take a stance to endorse or denounce this tactic because it does provide results.
While some may say this method is dirty, tainted, or just underweight marketing, it's being used by business everywhere to propel their site recognition and visibility. The point is not to consider any form of media as to small to be useful. Whatever addresses are applicable to your business or site should always be listed in Google, Yahoo, and Mapquest Map sites. Unless there are privacy concerns, this is an easy method at getting multiple links and search traffic to your site. If there are privacy concerns, it is quite apparent that a lot of businesses are using addresses that are not their own, not remotely related to the company, and in a few cases, don't even exist. Like I said, I don't take a stance either way on the address issue. Whatever address you choose to use is your own business and will be pertinent to your site needs. The pint is to consider adding site traffic through any means possible and to elevate your position in the search engines. If you find that having multiple addresses within search maps allows for extra exposure, it might be worth considering.