External Reset Button

I have nearly finished a project that uses serial communication between Arduino and Max/MSP. Everytime I start serial communications in Max I have to reset the board to get it to play ball.

I was wondering if I can solder an external reset switch that I could place on the outside of my enclosure so it's easy for me to reset on the fly.

Yes, if you want to reset, just bring the reset pin (right beside the 3.3V pin) to ground.

Unless you have done something to prevent it, every time you start serial communication, the Arduino resets anyway. That may be why you are having a problem.