While PowerTap may have experimented with insole-based power meters, RPM2 put their foot down and stepped into production.
They make versions for both cycling and running as well as a combo unit for triathlon/multisport use, and the cycling features make it fairly unique among power meter options. Garmin’s recent software update for its Vector pedals added a simple foot pressure balance measurement, showing if you were putting more pressure on the inside or outside edges of the pedal. Presumably, this data let you know if you’re feet could be better centered over the pedal for more efficient power transfer.
RPM2 takes this a step further (or closer?) by measuring both left/right and fore/after pressure, letting you see exactly where your feet are pressing the hardest against your shoe’s sole. This provides more specific and exact data that can be used to correct cleat placement, fit and alignment.
Of course, it also provides standard total power output for each leg, along with cadence and where in your pedal stroke your power is being applied…