We recently released an update to Sifter that included search, and despite the deceptively simple name of "search", it's actually a fairly complex feature. I wanted to run through everything involved in getting search up and running. This was written...
http://nextupdate.com/blog/archives/2009/03/implementing-search/We'll only send emails for significant product announcements, and those happen every couple of months at most. Of course, we won't give away or sell your e-mail address either.