This may or may not help but if you have access to a Mac you can use Quartz Composer for this. For example you can put a trackball and clear patch in a composition, add a glsl shader patch to the trackball and add add the a teapot patch to the glsl shader patch. Then if you go to settings on the glsl shader, you have access to the vertex and fragment shader code. Any changes you make will be displayed in real time. The only drawback is that as far as I can tell you have to use hard-coded constants instead of uniforms. It's not perfect but its fine for playing with new effects and rapid prototyping of algorithms.
