To keep on top of my reading, tests and other due dates, I've started using Remember the Milk. Initially I didn't get how useful it was. It looked like most other online to do lists. Once I played around with it and read this blog post from Legal Andrew, I realized it was what I was looking for.
I created a list for each class and entered all the reading assignments from each class' syllabus. After entering all the readings and their due dates, I gave them the tag, "readings". Then I created a search list titled "This Weeks Readings", whose search criteria were items tagged "readings" and due within the next seven days. To make RTM search correctly, your search syntax has to be correct. duewithin:"7 days" does not work, dueWithin:"7 days" does. Capitalization is important. I created a similar list for all tests, quizzes, midterms and finals, except I made the time frame of 30 days, and titled it "This Months Exams, Tests, Quizzes" so far it is empty. but it will give me enough time to prepare. The help file is excellently written and it will send reminders as well.