github.com/twotwotwo/sorts is a Go package with parallel radix- and quicksorts. It can run up to 5x faster than stdlib sort on the right kind of large sort task, so it could be useful for analysis and indexing/database-y work in which you have to sort millions of items. (To be clear, I don't recommend most folks drop stdlib sort, which is great, and which sorts depends on.)
While the process of writing it's fresh on my mind, here are some technical details, some things that didn't make the cut, and some thoughts about the process:
Concretely, what this looks like inside:
Both number and string versions are in-place MSD radix sorts that look at a byte at a time and, once the range being sorted gets down to 128 items, call (essentially) the stdlib's quicksort.
The [parallelization code