A few months ago I worked on HxSL which is a 3D shader language. I wanted people to be able to see how HxSL works and give it a try without installing Haxe and writing code.
With HxSL studio, you can modify both vertex and fragment shaders in an HTML page. The shader text get sent to flash component using Haxe Remoting on each change. Then I'm using HScript to parse the text before using HxSL compiler to generate on-the-fly AGAL bytecode.
Thanks to Haxe being very fast you can get realtime feedback on errors. Works very nice.
If you have an error, it will be sent back from Flash to JS so it can be displayed. If you click on the error you will select the HxSL part that is causing the error.
You can also see the AGAL output that you can paste in your AS3 code in case you're not lucky enough to use Haxe for your daily job ;)
This is actually not a fulled feature Studio as I wanted to built it. You have only one primitive which is a simple axis-aligned-cube and only 4 possible shader variables :
mpos: position matrix, rotate over time
mproj: camera projection matrix
time: time scalar
tex: perlin noise texture
I wanted to add an additional tab where you could define your own variables and modify them, then change the primitive among cube/sphere/etc..., and also upload you custom textures, but I'm lacking time to work on it so I wanted to release this working demo instead of waiting it to be complete.
If anybody else want to simply read the source code or is willing to implement the missing features, don't hesitate, it's pretty small so far ( 3 KB Haxe/JS + 9 KB Haxe/Flash - excluding libs) and available here : http://code.google.com/p/hxformat/source/browse/#svn/other/studio