Matt Hasselbeck and Kurt Warner come to mind. I also thought of Favre and Bailey but they were already mentioned. Wes Welker, Michael Turner, Priest Holmes... there are a good number.
I couldn't disagree more. Primetime came in as the rival to Bo Jackson b/c he played both baseball and football... and well. I definitely look at him as a Falcon before he decided to try to play for every team in the NFL.