For the previous months, I’ve been putting my spare time towards a new feature that I believe will greatly help adding free vector images. The feature is an online tool, that helps tracing raster images. It works by uploading your raster image, then tracing it online to produce the vector in a semi-automated way.
There are many useful tools available now, however none of them is able to produce what I percieve as a clipart. The tools that I regularly use are potrace (from inside inkscape) and sometimes vectormagic. The problem with both is that if you try vectorizing a colored image they will produce a fuzzy blurry svg, which does not look anywhere close to a clip art.
I had excellent results with potrace on lineart images, and I had no luck with colored ones.
This online tool solves a big part of the colored images problem. Some of the test results are here (showing both the raster and the vectorized result):