Just go to the HUD website:
Homes and Communities - U.S. Department of Housing and Urban Development (HUD)
It's all public info, and you can search individual states. But I've noticed that there aren't nearly as many listings as there were a few years ago, because investors have snapped up so many gov't-owned homes. I do believe you have to have a realtor submit your bid for you, but so what. It's not like their paycheck comes out of the buyer's pocket.
Regarding foreclosures, if you do a search on a site like ziprealty.com or redfin.com, the listings will tell you whether the house is bank-owned or not. These are free sites. But I'm not sure if you search directly for REOs; you might have to search within a particular price range or neighborhood, and see which ones are foreclosures. Or a realtor can just find some for you.