Thermal Imaging is a powerful tool for the home inspector.  It allows the inspector to detect conditions (moisture penetration from faulty roofing, leaking plumbing, leaking HVAC ducts) which are conducive to the growth of wood destroying organisms, areas which lack insulation, defects associated with electrical systems, and leaks in HVAC ducting.  As a certified thermal imager, I use this technology on every home inspection I perform.

The top picture is a normal digital photo of a hall ceiling stain.  The bottom pictures is a thermal imaging photo of the same area showing the presence of moisture (blue, cooler portion)

The above photos is of a wet wall with the thermal image superimposed upon regular digital image