Very often we here at OpenNETCF work on projects that are internal to companies that is seen by relatively few people or we do infrastructure work that helps an app succeed, but it isn't the app itself. Sometimes, though, we do get an opportunity to write public, commercial applications. We've just finished version 1 of Trapster for Windows Mobile, which chould hit the Windows Marketplace this month. For more info on what Trapster is and how it works visit their website, or read one of their reviews such as that on PocketNow or CNET.
The pieces of note here are that we used the OpenNETCF IoC Framework for dependency injection and the Bing Maps web services for all of the mapping and navigation work.