It's a great opportunity for lead to buy houses, fix/flip rent them out. Check in your local laws, probably have to to licensed, carry insuranced/bonded. Let everybody know realtors, banks, title company, that your in this business, pass our your card, market your business etc..
The banks use property preservation companies to service the foreclosures - so you might want to get acquainted with some of them.
Attorneys that handle estates might be a good lead source as well. But these will be sellers - listing in MLS usually doesn't look good with "stuff" inside the house.
The buyers at the courthouse auctions are another potential target. You meet them in person at the courthouse (or wherever the foreclosure auctions are held). Or if your county recorder has an online site AND the foreclosure auctions get recorded with a special deed that you can then search for specifically (like sheriff's deed or trustee's deed maybe) - then you can find them online even.