1. A brand name (that has become generic) for a type of Power Quality Analyzer, such as those from http://www.dranetz.com/power-quality-analyzers/ .
2. The theatrical supply company, BMI Supply.
3. Building Management Interface. Used in themed/architectural attractions to connect show control systems with a facility's energy usage monitoring systems. A "dawn/dusk" sensor, for example, might send a signal to the theatrical lighting control system to turn on/off lighting depending on daylight conditions.
4. Broadcast Music Inc. Along with ASCAP one of two major musical licensing entities. BMI collects royalties from end users and distributes them among the artists they represent. BMI.com