Firmata and Arduino2Max

For a lot of projects you might just want to use the arduino just as an interface to different applications, like max,pd,flash,vvvv,processing etc, and not worry about the programming of the arduino.

Firmata does just that: giving you control over the outputs and reading the inputs, and then there are different implementations for different applications. All you need to do is to upload the firmata firmware on the arduino as you would with any sketch, and then use the implementation for your application (maxuino for max, pduino for pd etc).

If you just want to use the Arduino as a sensor interface for max, you could take a look at Arduino2Max.