The Servant Engine is a community based open source 3D MMORPG Engine. If you would like to contribute to the Servant engine, Please visit http://modifiedservant.proboards.com. Or you may start a branch project and develop it any way you wish.
This is truly amazing. It provides a simple client and server engine, along with the tools you need. The simplicity is GREAT for beginners, yet it leaves tons of room for expanding and development for experts. I highly recommend this source.