I really didn't have to deal with this in college because most of my classes either had around 20 people in them, or were so easy that it wasn't worth worrying about. My girlfriend, on the other hand, has this same problem, and it pisses me off to hear her say people are doing this. You may say never be a snitch, but the cheaters are definitely detracting from your overall grade by boosting their grade if the teacher uses a curve. I tell my girlfriend that she should notify the teacher that people ARE cheating on the tests, but not to say who. I would consider naming names if it were me... they are hurting your grade, and if you don't know them, screw 'em.