We've only scratched the surface of the possibilities that Web service enablement presents. I expect there will be a plethora of samples on web sites and blog posts when NAV 2009 starts to take off and the NAV gurus decide to show off their skills. If you are non-technical, hopefully you found enough in this chapter to keep you interested, and you now have a better understanding of what NAV 2009 means in terms of extensibility. If you are a technical consultant and programmer, this chapter will provide a foundation for exploring the world of NAV 2009 and Web services, but there is plenty more for you to experiment with on your own.
Here're some more ideas you can try for homework:
Build a Codeunit that takes an XMLport as a parameter to allow a 'Create Purchase Order' service to be exposed as a Web service—try the same exercise using a BigText parameter.
Create an InfoPath form for creating new customers in NAV—for bonus points, you can deploy this to the Forms Server component of MOSS...