Serial not displaying sketch for MPU6050
Ground the AD0 pin. I thought the address should be set to 0x68 without this, but from what I've seen it fluctuates between 0x68 and 0x69. If you want the address to be 0x69 short the AD0 pin to 5V. I guess this would be useful if you need to use 2 MPU6050s with different I2C addresses without doing something in software. Haven't looked into that yet

Still, the I2C scanner for arduino may be useful for detecting the address/debugging: http://playground.arduino.cc/Main/I2cScanner