Amanda,
Good point. For instance, I don't favor extra credit. However, I'll add a bonus question to a test, usually in the form of an essay question, that allows a student the option of just spewing out all they can (accurately) cite about the topic. These meager bonus points are added on top of the total points for the exam. Also, I'll usually drop the lowest scoring quiz. Bot these measure provide a degree of "adjustment", without skewing the overall grades that much.
Barry Westling