I have, and it's usually word-of-mouth or social networking. There are frankly a bunch of folks who will ferry little airplanes for free (they may or may not have commercial certificates) and a bunch of owners who take them up on the offer, and generally neither one of them seems to know and/or care about the liability risks they assume when they do that.
The little amount of work I've gotten has come from shops or owners who already knew me, and while I did get some "hits" from advertising in Trade-A-Plane, they were looking to ferry unworthy airplanes (which I won't do) or airplanes that I don't have a lot of experience in, or wanted me to fly them across the Atlantic (which I also won't do just yet).
So, my experience is that there isn't a huge lucrative market for light aircraft ferry, but the occasional job is fun.