For one of my third year, fall 2011 university courses, my friend and I decided to make a multiplayer (both hotseat and networked matchmaking) version of Connect Four for Android! It was designed over a very short timespan, so very little effort was put into the interface. We used RabbitMQ for sending messages to / from the matchmaking server and unnecessarily used remote method invocation (RMI) to allow the matchmaking server to interact with an interchangeable database server. The program also features statistics tracking, game history and user accounts for players to use.
SVN Repository: https://subversion.assembla.com/svn/connect_4/
Download: Connect Four
Here are some screenshots of our version of Connect Four in action (click on any to view a larger image):