by benhur.goncalves @ instructables.com:
Hi folks! Last few days I’ve been obsessed with the idea to make my own watch from arduino parts, but something cool I could use and say I did it myself. So I found out there was a sensor board (commonly named GY-87) which had three sensors on it: HMC5883L (compass), BMP085 (pressure, altitude, temperature) and MPU6050 (accelerometer and gyroscope). With it, via I2C, I could add an Arduino Pro Mini, and an I2C Oled Display and make a watch capable of having all this information, plus a pedometer (by analysing accelerometer data).
Arduino Watch With Altitude, Temperature, Compass And Pedometer – [Link]