I highly recommend a movie called "Catfish" though it is not a documentary in the strictest sense. It's about a NYC photographer who is befriended on Facebook by a young girl from the midwest who is a painter. She's a fan of his work and asks permission to paint some of the images he's had published in newspapers. Their relationship grows and he also becomes friends with her mom and older sister, later becoming romantically involved with the sister. Everything is long distance, based only on Facebook and phone conversations. He decides to make a surprise visit to the family and finds that he has been very, very misled. This is a true story and is captured in real-time by the photographer's brother, who is a filmmaker. It is funny, heartwrenching and strange, I couldn't stop thinking about it for weeks after I'd seen it! Check it out if it's playing in your city! Such a unique film.

