1. A configurable thermometer comprising: a controller for operating the thermometer, said controller having a memory for storing computer-executable instructions implementing a plurality of functions of the thermometer; and a model selection device identifying a selected one of a plurality of configurations of the thermometer, each of said configurations of the thermometer being defined by one or more of the functions of the thermometer, said model selection device being connected to the controller and said controller being responsive to the model selection device connected thereto for operating the thermometer in the selected configuration, wherein the model selection device comprises one of a plurality of interchangeable user input devices, each of said user input devices and said controller having mating electrical connectors for connecting a selected one of the user input devices to the controller to configure the thermometer according to the selected configuration.