Our latest project is a C# Windows Mobile application (on a ruggedized device) for tracking/managing/auditing tree work for power companies and other similar domains.
I was approached by a client who recently saw a similar product in the field, and he asked if I thought it was possible to build one for his company. Replacing a paper-based, error-prone process with one that automatically takes pictures of the work and records GPS coordinates is a no-brainer.