I have created a online webgl edtior that let you play with GLSL shaders easily.

Read more about it here:
http://blog.nobel-joergensen.com/2011/1 ... a-browser/

And a more in depth article explaining the implementation:
http://blog.nobel-joergensen.com/2011/1 ... er-editor/

The editor is open source and free to use.

Comments are welcome