Listing publications pretty much goes without saying. This demonstrates not only knowledge of the technology you wrote about, but also the ability to communicate well, which is a big plus for many employers. I list my book on my resume as well as some of the presentations I've done. The latter also highlights my ability to communicate, and the fact that I'm considered to have sufficient expertise to be worth listening to at a conference.
I also list all my Free Software work, as well as the community work I've done (like helping create jobs.perl.org). Listing the Free Software is great, because it gives employers a chance to easily check out code examples. Even better, they may actually be using some of your code, and not have realized it. I list other work just because it can't hurt to point out my community involvement.
Empirical evidence definitely supports the idea that participating in Free Software projects helps get you work. Being part of the Mason core team has led to more than one person getting in contact with me about consulting work.