std.parallelism: Call for benchmarks

[dsimcha]

Andrei asked a while back for me to motivate the inclusion of 
std.parallelism in Phobos with some benchmarks.  I've been putting this 
off because I can't think of many good ones.  Pretty much everything 
I've thought of falls into one of two categories:

1.  A full-fledged real-world example (mostly from my thesis research) 
of where I've used std.parallelism.  These are way too complicated, have 
way too many dependencies, and are way too far from the kinds of 
problems that most programmers are familiar with to serve as motivating 
examples.  Most of them involve algorithms for analyzing 
genomic/transcriptomic data of some kind and are hundreds or thousands 
of lines of code.

2.  Something so trivial that nobody would ever actually parallelize it, 
and that probably wouldn't parallelize well because the parallelism is 
ridiculously fine-grained and/or the computations involved are more 
memory bandwidth bound than CPU bound.

Russel Winder has shown a decent pi-calculating benchmark, which I'd 
like to use with his permission.  Could anyone else please submit some 
benchmarks, or at least some ideas for benchmarks that are simple enough 
to serve as motivating examples, yet non-trivial enough to be worth 
parallelizing?