Remember the Blender web plugin from long ago? Like a veritable phoenix, it has risen from the ashes and been brought back to life!
Erwin "Physics" Coumans writes:
After many years, version skip from 2.25 to 2.42, Internet Explorer ActiveX control is working again, including the new Bullet rigid body dynamics and vehicle physics. Future steps might include improving stability, adding Firefox and COLLADA 1.4 import support.
The site has not only the plugin download (for IE) but also a guide to creating content. Get it here!