Since the birth of the internet, web sites have been constructed from HTML(HyperText Markup Language). Displaying web sites was a simple process that consisted of taking data and rendering static information to the users screen.
Things have become much more complicated, with animation, AJAX - a method of getting data from the server without reloading the page, and CSS (how web pages are 'styled'/themed'), yet the method in which these pages are displayed haven't changed but have been expanded. We still use HTML.
As of March 2011 with initial participation from Apple, Google, Mozilla, Opera, and others the Khronos Group released WebGL, which enabled browsers with support for HTML 5 to access a computers GPU(Graphics Processing Unit).
What does this mean exactly?
It means that powerful graphics card in your computer that renders your video games can now be used in a web browser. This is a huge advancement in web presentation that has yet to be fully utilized.
The Problem and the Opportunity:
WebGL is based off of OpenGL and is an API to make low level graphics calls. There isn't a framework that exists yet to simplify these calls and support web like presentation abilities.
Imagine if facebook or google had the ability to present information in a 3d world with any effect you can think of or imagine.
If you've ever tried to "style" a web page you know how tedious it can be just to add rounded corners to a box or to get something to look a particular way. It's difficult and imprecise.
A good exmple of what's possible can be seen here:
If I wasn't working on my game engine I'd be all over this.