Hello,
I'm happy to announce WebGL playground, an online tool for playing with WebGL. I hope it will be useful for many of the forum readers!

http://webglplayground.net

It's work in progress. I'm open to suggestions

some more details:
WebGL playground is a straightforward idea: type in
your WebGL script and see the results. But the cool
part is that the editor and the results are just on
the same page and that you get a handful of features
that make your life easier.

The editor lets you work on the JavaScript code and
the GLSL vertex/fragment shaders (if you have any)
at the same time in a convenient way. Everything is
organized, formatted and highlighted properly, just
as you would like!

You can use arbitrary JavaScript libraries to create
your effects, combine multiple fragment and vertex
shaders, handle user input etc.

Thanks,