Unity 3 is a game development tool, originally intended designing and building video games. In practice, Unity can be used to create virtually any type of interactive 3D environement. This includes walkthroughs of 3D data, virtual museums and archaeological sites, reconstructions of architecture, simulations, and almost anything else you can imagine. At the University of Arkansas Prof. David Frederick is using this software on the Digital Pompeii Project. Researchers at CAST are using Unity to build reconstructions of Historic and Archaeological Sites. More information on these projects coming soon!
Information from Unity3D website: