3DVia (Dessault Systemes) have recently made a couple of new services available for free (currently) including
3DVia Scene - a 3D chat, community, collaboration, browser based viewer (may be a bit buggy. It froze IE7 a few times when tried. Not tested with Mozilla based as of yet). And
3DVia Studio - a game and interactive development suite; Studio looks and works a little bit like Unity3D, having similar project capabilities. Both allow collaborative project development to varying degrees with Studio being geared more towards that rather than individual stand-alone applications although 'games' can be made with it. At present the applications are in public 'beta' but there does appear to be plans to make both available for licence (else you have to upload content to the 3D communities depository via a profile you need to create). Various documentation is available for Studio, including
tutorials,
reference and
demos.
