VR Juggler is a virtual platform for virtual reality application development created at the Virtual Reality Applications Center at Iowa State University. Applications developed in VR Juggler can transparently move between a wide range of VR systems.
VRS is an environment for presenting three dimensional (3D) world. All visualisations are made at client(s) side VRC (Virtual Reality Client - example client is under developement, SF site avaible, see also http://jvrc.info).
VRMoo can be summed up as such: Virtual Reality Object Oriented MUD. I intend VRMoo to be capable of simulating complex environments, allowing real time 3D interaction with these environments, and allowing real time 3D interaction with other users.