I saw the host of this show on The Jay Leno Show. The show features people who pretend to be someone else online and get into "relationships" with other people online. The story they showed was a woman who gets "involved" with a guy, the guy kept avoiding meeting. Finally, through the help of this Catfish show, they tracked down the guy. [OK, I don't understand why people agree to go on TV like this]. The guy turned out to be a married woman. And to top it off, they had talked on the phone! And, she had done this many times before. 

Apparently, there are enough people doing this that MTV has a whole show about it!

I dunno, just kind of brought back memories of this very board...