VRML is OK, but I have a sneaky suspiscion it might just be a microsoft thing that won’t work elsewhere. But I don’t know.
One thing I do know for certain is that Java3D is REALLY easy to use (much easier than OpenGL) although its performance is not the best. Take a look at http://java.sun.com/products/java-media/3D/index.html
Java3D has a really nice way of representing things, using a scene graph - this leads to a very easy to understand object-oriented way of thinking.
Problem of course is that people would have to download the Java3D class files from your site the first time they looked at the page…