Developing a google maps mashup tool can be a great way for driving traffic to your site as well as building back links to your site. If you have some industry specific data, try and think of a way you could use it on a map. Keep in mind that developing a useful online resource like this can help drive traffic to your site permanently, this make such tools far more valuable than paid advertisement that may only last a day or a week.
See this example of this map that we developed. After Launching this map mashup we saw a traffic spike of over 300 unique daily viewers. If you don't have any ideas Contact Us and we can try and help you out.
Creating a google map mashup or even a full blown application can be a great way to drive traffic to your site or can even become a business of its own. Our developers are highly experienced in developing with the Google Maps API v3 , and we look forward to helping you with your next project.