Oh god, so many.
I did English Lit, Latin and Philosophy in first year; I remember I had a Latin grammar class at 9 on a Friday morning which I went to maybe twice or three times in the whole year. Though to be fair, everything they taught in that class was stuff I'd already seen in secondary school/college, so there wasn't much point in going.
I missed quite a lot of English Lit lectures as well (I always went to the seminars though), whenever I felt my time would be more efficiently spent doing coursework or reading on my own than going to a lecture that didn't seem extremely interesting.
I always went to the Philosophy lectures though.
I did fine in my exams.