I've been using recruiter spam as an opportunity to promote my own project just by replying and asking them to check it out. While the total number of responses are small, I've gotten some decent feedback and made a few interesting contacts through this tactic.
I'll be adding Hacker Dojo's note to the end from now on.
[recruiter name],
Thanks for reaching out. Unfortunately, I'm not looking for a new position as I'm focused on my latest project, http://iwaat.com. I'll keep you in mind when I begin hiring. In the meantime, if you have any feedback...
I'll be adding Hacker Dojo's note to the end from now on.