I would like to add to this list the Embree raytracing library by Intel. I already mentioned this in another thread but it got no attention at all.

This library, as its name indicates, is a set of fast raytracing algorithms developed by Intel.

http://software.intel.com/en-us/articles/embree-photo-realistic-ray-tracing-kernels

This library has been deemed worthy and reliable enough that Maxon implemented it in its Cinem4D R15 release, resulting in some significant speed improvement - up to 300% - in Cinema4D's already super-fast renderer

http://www.youtube.com/watch?v=rJd-WEtkg-

The implementation of this library in Carrara's renderer could give it a much needed speed boost - probably in the 1000% to 2000% range - and would enable us users to finally use Carrara's GI without waiting 2 days to render just 1 frame, and I'm talking here from personal experience.

This isn't a featurette, but its implementation in Carrara shouldn't take more than 4 to 5 months for one developer, and at this price it would be a great added value to Carrara, because it could make its renderer speed comparable to the likes of Cinema4D.