Accelerometers and gyroscopes are commonly used sensors where some sort of balance is needed. Combination of both in one board is called IMU (Inertial Measurement Unit). You will find one on flight controllers, balance modules and in many other areas. If you are going to build something from scratch then you should know some background information on how to interpret readings and how to use them in control. Gadget Gangster have shared pretty good instructable where he explains how to interface IMU device to microcontroller and how to use this data to get desired results.
As example he uses Acc_Gyro board with LIS331AL triple axis accelerometer and LPR550AL dual axis gyroscope. He goes through some math while explaining how to determine orientation of IMU using either only accelerometer data or combination with gyroscope readings. Plus gyroscope gives some clue about rotation around one or another axis. SO if you are thinking of building inertial system, you should do your homework and understand hos things work.