Hmm... I've been to the xj3d website, and to be honest I don't understand what it even is. From your description it sounds like that's what I've been looking for, but it also sounds like it would take some figuring out too. I'll probably fool with it over the weekend.
As a matter of fact, yes, I can also export to OBJ as well as PLY and VRML. Unfortunately, I don't know how to put these on a webpage either. As an OBJ there is a loss of color information, but that's acceptable if I can make it work. I'll also have to check out the HTML5 canvas as you recommended.
Feels like someone has given me all the pieces of a car and told me to put it together. I have the vision of the car and generally how it goes together... but when I get down to "attach A to B"... I get kind of lost. I guess this is why the people who normally fool with this kind of 3D modeling stuff go to school for it.