Hi daigoro,

There are several applications which allow you to do this (in different ways).

RPS 3D PDF which is not free but the most cross platform tool. It will - as it says create 3D PDF files which you can then orbit etc. Hypercosm - which has a free and a commercial version as well. Not available for Macintosh at the moment - and needs a (downloadable) plugin to see the models. eDrawings - but it only works on IE (and I'm not sure if it is embeddable in a website)
See some discussions in the respective subforums about them here.