ANOTHER ROTISSERIE LEAGUE THAT IS AS OLD AS OURS. I checked out the wikipedia entry on fantasy baseball.
The entry identifies another league which has been in continuous operation as long as ours has been: “The oldest continuously operating Rotisserie league in the world is the Roach Motel League, founded in 1981 at Columbia University in New York. Original Rotisserie League member Glen Waggoner was an administrator at Columbia and he passed along the rules to a group of undergraduates. The Roach Motel League, still consisting primarily of original members, has held a draft and played the game every year since 1981.”
So there were at least two fantasy leagues in 1981. According to the wikipedia entry, there were over 11 million people playing fantasy baseball as of 2009.