Daniel J. Bernstein is the author of the QmailSystem, contributor in many fields (especially mathematics), and all-round genius.
Re: comment on the QmailSystem page: "DanBernstein is a genius programmer" - he's a genius in general, and a leading/rising light in algorithmic number theory (including cryptographic applications), too. I've found a surprisingly large percentage of his research to be not just interesting, but actually directly useful in real world applications of number theory as well.