Ever wonder what lives in your gut? The American Gut Project aims to find out exactly what bugs lurk inside your intestines, inside your mouth, on your skin and other nooks and crannies of the human body. Following a seven-day diet questionnaire, participants must, yes, send in a fecal sample, along with a mouth swab for testing. Pretty cool, huh? They would like to explore the microbiome of the entire world's population, but shipping poop through international mail turns out to be tricky/illegal.