WebGL - YES!

First, go here to update your Firefox (or use Chrome):

http://www.mozilla.com/en-US/firefox/all.html

In firefox 4.0, you have to enable this feature manually,

First type in "about:config" in the address bar,
     Don't let it scare you,
     Sort the items by name,
     Find the "webgl.force_enabled" and double click that to make it true.

Now, go find some sweet OpenGL ES 2.0 type demos.

!!! ACHTUNG !!!

--> Make absolutely sure you have the NoScript AddOn (http://noscript.net/) for firefox first. This will allow you to STOP content from automatically loading, just in case you are like me and are trigger happy.

http://www.khronos.org/webgl/wiki/Demo_Repository
http://www.chromeexperiments.com/webgl

This is great because it eliminates the need for stupid plugins like Unity, Flash, Shockwave, Java, ect...
Now you can use the ECMA script (Javascript) built into the browser to make full powered 3D games, which now are compliant to any browsers that use them!

This is serious cool. I'm totally making something in this.

-Z