I've been using Uncalendars since sophomore year of undergrad! I used the small size for 3 years and between scheduling for classes, research and some clubs, it was perfect. For graduate school, I purchased the larger version, for scheduling/notes for TA'ing, running the lab, etc.
I love that there aren't dates already filled in, so you can start using it whenever. It's a little overwhelming when you start, simply because there's so many boxes and I had no idea how to organize everything. But one or two weeks in, and you'll be fine!
http://www.uncalendar.com/index.jsp