Why do my transactions show I received 1 satoshi?
That particular transaction is an attempt at something that has become known as "dust spam". The idea is that the sender sends a very small amount of bitcoin to many different addresses, hoping that people will notice and investigate further. It's possible to find out who sent this if you look hard enough, but most people won't bother. The effectiveness of this kind of spam is clearly limited.

For more information, see the Reddit thread PSA: Did you receive a "dust" amount of BTC from "Enjoy" and "Sochi"? Here's why.