I've been using them in my project for a while now. I have a simple wrapper for OpenMP [here](https://github.com/jcosborn/qex/blob/master/src/omp.nim) and some SIMD wrappers [here](https://github.com/jcosborn/qex/tree/master/src/simd).
The SIMD stuff is still a bit of a mess now, but may eventually make it into a separate package.
