How can you profit from a downturn in the economy?

[Kris Klark]

I am new to the world of real estate investment and am trying to build a solid foundation of knowledge before I start making any deals.  My interest is broad and I could really go in any direction as far as "choosing a niche" goes. 

My question is this:  How can you protect yourself from a downturn or even crash in the economy? Is there anything in the world of real estate that is equivalent to shorting stocks?

It's been my experience in life that there is always someone making a profit when everyone else seems to be losing, it's just a matter of being clever enough to figure out how to be that person.  Are there any investors on BP that somehow profited from the crash of 2008, or is there any advice from someone who learned the hard way?