Patriots bandwagon team of the 2000's.
Cowboys bandwagon team of the 1990's.
San Francisco 49er's bandwagon team of the 1980's.
By bandwagon, I mean great teams that are very popular because of winning. For example, The Patriots were a decent team prior to Bill Belichick and they had only local support until they won their first championship. Now everywhere around the country there seems to be a Pats fan or a Cowboys fan.
Cheer for the Giants. Great Defense with an inconsistent QB.
Or, just become an NFL fan. Ever since "fantasy football", there are a lot of fans just following their favorite players. They watch most NFL games without being too loyal to anyone team.