An archeologist. I wanted to carefully sift through dirt for years trying to figure out stuff about lost civilizations. I did end up in science, albiet a different field, after a brief detour into computer engineering.
Moe, be glad you didn't get into nuclear physics. As a subfield of physics it has become a rather dead animal (actually, if you don't mind working for the military I'm sure it is still a good field, come to think of it). Most people have moved on to high energy particle physics where collaborations are larger and listing the co-authors can take a journal page.
trunks, ever though of becoming an historian? I assure you there will be no problem finding a job teaching history, but why not try to be the guy who writes the books?
In history class you learn "this is the way it was, m'kay?" whereas being a historian you are exposed to all the evidence and have to try to make sense of it - even the parts that contradict each other.