Almost 20 years ago there was VRML, good for demos.
Every phone now is much faster than high-end workstations back then...
still no "real" VR, but we are getting closer...
WebVR - Bringing Virtual Reality to the Web
aframevr/aframe @ GitHub
Introduction to the VR Web | Just A/VR Show | Channel 9
Interactive 3D Graphics Course With Three.js & WebGL - Udacity
Web3D Consortium | Open Standards for Real-Time 3D Communication
Bringing Virtual Reality to the Web: VR, WebGL and CSS – Together At …