I think fully 90% of the home inspections I have done this year have been vacant properties that have either been foreclosed or are in a short sale. Earlier this year I did a vacant property that was actually in pretty good shape. However, when I came down from the attic, I showed my Clients the following picture:

I told them that they might be able to find something valuable that they could sell on eBay to help with their mortgage!
Several years ago I was under a house out in Ocean Beach and found a huge collection of soft drink bottles from Pepsi, Coca-Cola, and others, all pre-World War II. I brought a couple of bottles out with me and told them that they should be able to sell them and make a little bit of money. When I went to their house-warming party a month after they closed escrow, they informed me that they had found over 500 bottles in the crawl space and had sold them for $22,000. They also presented me with a 10% finders and consulting commission, which was appreciated and totally unexpected. I didn't do anything other than advise them on the finding and how to dispose of them. I sponsored a party for my employees with the money and bought a couple of spare ladders, flashlights, and digital cameras.