MPU-6050 6DOF 3 Axis Gyroscope and Accelerometer Module for Arduino

The InvenSense MPU-6050 sensor contains a MEMS accelerometer and a MEMS gyro in a single chip. It is very accurate, as it contains 16-bits analog to digital conversion hardware for each channel. Therefor it captures the x, y, and z channel at the same time. The sensor uses the I2C-bus to interface with the Arduino.

The MPU-6050 is not expensive, especially given the fact that it combines both an accelerometer and a gyro.

Also note that Invensense has combined the MPU-6050 with a magnetometer (compass) in a single chip called MPU-9150.