Shadertoy is a web tool that allows developers all over the globe push pixels from code to screen using WebGL. It is free for everybody and it is accessible via www.shadertoy.com.
In less that two years, our users have created thousands of fragments shaders that explore a wide variety of real time graphics algorithms such as raymarching, procedural texturing, modeling and animation, fractal geometry, image compression, volumetric rendering or motion blur.
Shadertoy is also a social platform, a place for professionals and students alike to learn and teach about visuals, interactions, reactivity, modeling, GPU internals and shading.
What is SIGGRAPH? From Wikipedia:
SIGGRAPH (short for Special Interest Group on GRAPHics and Interactive Techniques) is the name of the annual conference on computer graphics (CG) convened by the ACM SIGGRAPHorganization. The first SIGGRAPH conference was in 1974. The conference is attended by tens of thousands of computer professionals.
Watch here the teaser trailer for Real-Time Live! – SIGGRAPH 2013 :