BMP180 Barometric Pressure/Temperature/Altitude Sensor: This precision sensor from Bosch is the best low-cost sensing solution for measuring barometric pressure and temperature. Because pressure changes with altitude you can also use it as an altimeter! The sensor is soldered onto a PCB with a 3.3V regulator, I2C level shifter and pull-up resistors on the I2C pins. Read more.
Triple-axis Accelerometer+Magnetometer (Compass) Board – LSM303: We based this breakout on the latest version of this popular sensor, the LSM303DLHC. This compact sensor uses I2C to communicate and its very easy to use. Since it’s a 3.3V max chip, we added circuitry to make it 5V-safe logic and power, for easy use with either 3 or 5V microcontrollers. Simply connect VCC to +3-5V and ground to ground. Then read data from the I2C clock and data pins. There’s also a Data Ready and two Interrupt pins you can use (check the LSM303 datasheet for details) Read more.