The easiest way I could think of to do it right now is go to Zillow.com, enter your search and then around the top middle there's a button called 'Listing Type.' That'll give you the option to only see the foreclosure, and if you need more info on the house you could just search public records.
IMO Zillow is not good. Always be aware that you get what you pay for when using a free site. IMO one of the best sources is Realty Trac. It is a subscription site but the cost per month is reasonable. I use a site (paid) that is specifically for the western states but have also used Realty Trac. Also, it provides information on real estate in general and foreclosures specifically.