Great question - we believe there are a lot of potential add-on modules, especially around building control. One that is gaining a lot of interest recently is using people-counting data to more precisely control HVAC systems (most systems today rely on simple motion sensing for control).
Modulating heating / cooling based on the exact count can help cut energy consumption, sometimes by as much as 30% for commercial buildings.
ARPA-E (Advanced Research Projects Agency) recently put out a proposal for such a system - you can read more here if you're interested: