Tinkecad has been turning up the awesome dial on their WebGL browser based 3D modeling application over the past year but they just made it even better with the ability to import 3D STL files....
This will make it SUPER easy to customize an existing 3D model to 3D Print at Shapeways, whether it be your own file you have created in another software, or a downloadable file from Shapeways, or other 3D model repositories like Thingiverse and GrabCad. You can also grab multiples STL files and mash them together, add text, geometry, anything.... AWESOME.
One limitation is the STL import is currently limited to 25,000 triangles so don't go throwing zBrush madness at it just yet, and of course, make sure you have permission to use the 3D files, and if you modify them, be sure to adhere to the terms by which the original 3D model was shared..
Thanks to the Tinkercad crew for such a fantastic move.