This is an MD5 library for the Arduino, based on scottmac's MD5 library, which you can find here: https://github.com/scottmac/arduino
I created this because I was having a really hard time finding an easy-to-install and use libray for the Arduino, so I decided to make my own. There is an example on how to use it.
Create a folder named MD5 in the libraries folder inside your Arduino sketch folder. If the libraries folder doesn't exist, create it. Then copy everything inside. (re)launch the Arduino IDE.
You're done. Time for a mojito