This pressure sensor from Freescale is a terrific sensing solution to precision measurement of barometric pressure and altitude. The MPL3115A2 includes a normal 1.5 Pascal resolution, which may resolve altitude at 0.3 meters (compare to the BMP180 that can perform 0.17m). It has some upsides compared to this BMP280, for example interrupt outputs for ultra-low electricity usage, and its also a heck of a lot easier to read altitude with a built in altimeter re - no calibration reading and calculating required. As a bonus, there is a fairly excellent temperature sensor with ±1°C typical accuracy (±3°C max).
This chip likes to be used with 2-3.6V power and logic voltages, so we placed it onto a breakout with a 3V regulator and logic level changing. Its easy has i2c capability.
This chip looks and sounds a whole lot as the MPL115A2 but this really is the precision version, which can act as an altitude-sensor in Addition to barometer.