What I have in my own pockets:
Right pocket: I almost always have four cards with me: driver's license, military ID (my dad was in the military, years ago, which is why I have it, and I go to school, which is how I keep it), university ID, and credit card. Sometimes I may have other pieces of paper in there (receipts and stuff), but I just about always have those cards with me.
Left pocket: Basically this is what doesn't go into my other pocket. Whenever I had my dorm key, it would go in there all the time. Pieces of paper can go in there as well...
If I carry cash with me, it can go in either pocket. Same with my cell phone (though if I carry my bookbag with me, then the phone goes into a pocket in there).
This is only when I'm not at home, though. If I am, then there's the good chance my pockets are empty. :P