SnappyTree is a WebGL-based procedural tree generation app by Paul Brunt, of GLGE fame.

It offers a bunch of neat presets, along with 20+ parameters that affect the trees ‘growth’ and texture. Your resulting tree can be output to JSON (for use with proctree.js), or the Collada / Wavefront formats, for native use.

If you’re interested in learning more about procedural object generation, this Wikipedia article on Lindenmayer systems may be of interest

SnappyTree

Mozilla DemoStudio detail page

proctree.js