One of the best ways at the present time to substantially increase the exposure of your website is via the Google Maps system in general, and Google Local in particular.
These type of advertising spots are becoming increasingly popular since they essentially put you on top of the regular search engine results, much like a good pay per click campaign, yet at minimal cost.
Unlike a PPC campaign, however, it usually takes some time to be listed in Google local. In addition, the project is still in beta so your listing could be altered over time as they change their business model.
It should be noted that besides Google, both Yahoo Search and the MSN Search Engine have their own unique versions of local listings as well.