Now that SQL Server is compatible with the data geometry and geography types natively in SQL Server 2008 (and later) relational engine, developers and DBA are the types of data used wisely. There are many useful applications for spatial data types, and if you're not using, probably in the near future. If you have never seen a well designed application based on spatial data, I encourage you to take a look at toxicrisk.com, a website that displays the sites registered by the EPA toxic waste in the U.S. USA.