I know I've bought several games because I watched or read Let's Plays on Something Awful or YouTube and enjoyed them, and so bought the game or its successor.

I know I've bought several games because I watched or read Let's Plays on Something Awful or YouTube and enjoyed them, and so bought the game or its successor. Three examples that come to mind are Arkham City (watched the Arkham Asylum LP), Europa Universalis (read an LP after playing CK2 a few times) and Assassin's Creed II (watched an amazing LP of Assassin's Creed I)