A Decade Box can be used for sensor simulation. The majority of temperature related sensors used on aircraft are resistance based. Resistance substitution can come in very handy for troubleshooting numerous systems. Window heat, cabin temp/control, engine indications, and overheat warnings are among some of the uses for a decade box.
Decade boxes can also come with capacitance and inductance substitution. I have found no uses for either.
Most resistance substitution boxes are not designed for power applications, ½ watt is the usual maximum power. Aircraft systems that use resistance for temperature measurement rarely exceed this value.
Just as a note: Caution should be followed when substituting a resistance for window heat sensors. The window can easily overheat and crack.