I think rugby should be more popular in America. It's a much faster paced football without passing.
I also think cricket can be a second or third tier sport in America. Every one grew up playing stickball as kids and that's roughly what it is as a sport. It was confusing as hell to watch, but once I read how scoring took place it's a really great game to watch.
Most of these sports played in other parts of the world won't catch on here, because their either really seasonal or expensive to have as recreation.