But I usually refuse: it seems to me that most of these people have just not bothered to take notes in class, or to read the assigned reading, and want my notes as a shortcut to passing the exam. I hate to take part in that, so I don't cooperate.
Some of them just cheerfully ask for the notes, some are apologetic and offer mumbled explanations, some plainly and obviously lie (e.g. a person who told me she lost her notebook and all her notes, when I know for a fact that she never took notes in this class).
I do like helping people, and I gladly e-mail people class notes for specific lessons they had missed, but I also believe in the important of individual academic work. If these people are not serious about this course, there's a good chance they're not serious about other courses, and helping them get away with it is helping to promote bad scholarship. I want no part of that.
I hate having to refuse, though. It's unpleasant. Obviously the refused may like me less, but that's not the main issue -- I'm willing to lose popularity for my ideals; it just feels unpleasant to refuse a plea for help, however justifiably. I wish they'd just stop.