You could go the vulture route and follow up on bankruptcies, while many are already in trouble some don't find out they are upside down until they file.
Contact non-profit financial counselors, people contact them for help, leave cards there and make friends.
I knew a vulture Realtor that followed court convictions, some are homeowners get sent up the river to the big house, the bread winner is gone and they are forced to sell. With values down, they could be short sales.
You could be a storm chaser, damaged homes that don't get sufficient insurance proceeds can easily be under water...so to speak.
Factory closings or employors closing, put a flyer on the company bulletin board. People may be moving away.
Look for contractors going bust, an unfinished home is always under water compared to market values.
A short sale is when the lender accepts less on a payoff.....so what do note holders do when they want to sell the note? Contact the buyer and see if they will sell in connection with a note sale......it's the same thing....kinda!
Good luck and good night....