These tiny gearmotors are available in a range of gear ratios. All of the micro metal gearmotors have the same physical dimensions, so one version can be easily swapped for another if your design requirements change.
This combination deal contains most of the parts you need to build an Zumo Arduino robot. It consists of a Zumo Shield for Arduino, a Zumo chassis kit, and a Zumo blade. This programmable robot can be used as an autonomous robot.
This is a 4WD IG42 single bearing platform that includes autonomous GPS navigation. A full array of sensors including a Pololu IMU, motor encoders, and a Garmin 18x 5 Hz GPS that work together to provide waypoint navigation with up to 3 meter accuracy.
The InvenSense MPU-6050 sensor contains an accelerometer and a gyroscope in a single chip. It is very accurate, this sensor is used in self balancing robots, drones, smartphones, etc. The sensor uses the I2C-bus to interface with microcontroller.