OK, so when looking at pre-foreclosures you have a few types of strategies to work with:
Short Sale (some equity)
Subject - To (low equity, possible upside down)
Wrap (some equity)
Fix and Flip (mid to high equity)
Wholesale (high equity)
If you are looking at a subject - to, the key is having a strong knowledge of the entire system AND a rockstar title company. You can always ask around for referrals, or just call your local title companies and ask them if they can handle doing subject-to's. It's a great strategy and most importantly CAN work with upside down houses. That's really crazy when you think that you CAN make maybe $10k on an underwater house.
Later today I am contracting (knock on wood) a guy that owes $170k after a loan modification on a house with an ARV of $160k. Is it going to be tough to finish the deal... yes, absolutely. But I may very well end up monetizing a house that is 2 weeks from foreclosure, and $10k upside down. Or I may spend a lot of time and get zip for it. That's the fun, I just don't know yet!