You have more bacterial cells living in and on your body than you have human cells.

If you judge based on cell count or DNA diversity your physical being is more bacteria than human. (If you go based on weight, human cells still predominate.)

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UPDATE: By coincidence article in WSJ today on this same topic. http://online.wsj.com/article/SB10001424052702303410404577464961870114758.html

Fun facts:

• 10,000 species of microbes that healthy people share their bodies with
  
  
• 200-pound human will contain bacteria weighing 2-6 pounds.

Researchers said Wednesday they have produced the first comprehensive genetic map of the microbes that live in or on a healthy human body, ... an effort to better understand bacteria and other organisms that play a critical role in processes ranging from digestion to infection.

Scientists know the body harbors trillions of such microorganisms—indeed, they outnumber human cells 10 to 1. But until now, they didn't know what all the bacteria were, where they were and how they might differ from person to person, or from site to site on a single body.