Just thought I would throw out a list that seems to be doing well for me. In my market and most mid-west markets, people that purchased a home in 2005-2007 paid on the very top of the market. I have access to RealQuest Professional and can pull list much like ListSource. By putting in filters such as purchase date from 2005-2007, Single Family, FHA or VA mortgage, I get a list of homeowners that put very little down and bought at the top end of the market. These types of sellers either don't think they can sell their home or if they are relocated turn into landlords and not by choice all the time. If you can get them to agree to 3-5 year RTO's and the numbers make sense it's been a good lead source.
If you don't have access to RealQuest or don't want to shell out the coin for ListSource look the county website. I am able to pull by a lot of free data from the Wisconsin county websites....California not so much, most of them require you to pay.