One of the best sources of example code for all LabVIEW code, including NXT, is the NI Example Finder (LabVIEW Help menu » Find Examples...). If you browse to Toolkits and Modules » NXT Robotics, you'll find a host of examples that illustrate each component of a successful NXT Robot control system.
Also take a look at the LabVIEW LEGO® MINDSTORMS® NXT Module Programming Guide and the Getting Started with the LabVIEW LEGO® MINDSTORMS® NXT Module documents for lots of helpful information.
All the best,
Fred V -- Product Support Engineer -- LabVIEW R&D -- National Instruments