Looks really good, but I fear the name might be a bit deceiving. I've found most Java libraries start with J, and most JS libraries end with JS(processing.js, popcorn.js, three.js), so I initially disregarded it as a Java library when I was just skimming the page.
The Unity 3D export is fantastic.
Here's hoping that webGL gains full traction.
You might want to change the name. J3D is already taken by Java 3D.