Here we have a free Excel Workbook that you can use to map your address data in Google Maps. You can use this spreadsheet as a standalone tool or add the components to your existing Excel workbook.
Download Excel Google Maps Workbook (30k)
Because this uses the Google Maps API it is subject to their terms of use and is limited to 15,000 requests per day.
How does this work?
We use the Google Maps version 3 API called from within the Microsoft Web Browser Control. The HTML file is hosted on our servers and contains the JavaScript call to handle the geocoding and plotting of points. The workbook contains example address data that you can replace with your own address information.