"Everybody is into geocoding today. Once you have the latitude and longitude of a location, you can start to do some really interesting things. But the problem is that if you have a large database of addresses to geocode, the various web-based APIs are not your friend. Not only is there a lot of latency involved in each webservice call, they are also rate-limited and consequently geocoding several million or more addresses simply becomes unfeasible."

Fast Geocoding of Addresses in C# with MapPoint