I got my current job by posting on a "who wants to be hired?" thread. I was contacted by the person who ended up being my manager and got fast tracked through the interviewing process. It's at a company that I probably never would have heard of otherwise (Fullstory), but I like it enough that I'm still there ~4.5 years later.

On the flip side, I can think of three people who were hired via "who's hiring?" posts I put up.