I'm looking to power 2 small hobby motors that each use 3V. I'm wondering how much voltage exactly a digital pin will output when i set it to High for controlling the motors.
This is for a small tank tread robot that will use Ultrasonic sensors for guidance.
Thanks for any and all help 
I'm wondering how much voltage exactly a digital pin will output when i set it to High for controlling the motors.
If it's a 5V Arduino, the pins will be 5V. They will provide less than 40 mA without damaging the Arduino, though, so don't expect to drive the motors from the digital pins.
At the very least you need to use a transistor to sit between the Arduino and the motor. The Arduino can operate the transistor as a switch and the transistor needs to be selected so it can comfortably carry the current required by the motor. Remember electric motors draw maximum current when they are stalled.
If you want to make the motor drive forwards and reverse you need to use a h-bridge such as an L298 chip. Googling Arduino h-bridge should find you lots of examples and products.
...R