List Of Game Engines
G3D Engine – good tool libraries, large free model collection
Torque Engine – very popular with independent developers
MMO Specific Engines
Unity 3D – in browser 3D MMO games, also has iPhone and Wii capabilities for additional licensing fees
Irrlicht – i really like this one, runs fast, lightweight, nice toolset
Ogre 3D – i found this one to be way too complicated and not very well planned out