Recently, some of my colleagues bemoaned the effort of making up exams at the end of the term. I wanted to share a trick that I have used, that makes creating exams much easier. It might work for you too.
I work on exam questions throughout the term rather than waiting until the end. A TA is assigned to each lecture, and is required to make up a couple of questions during or immediately after the lecture. This way, we get ideas that pop into the TA's head but that might have been forgotten by the end of the term. Another excellent source is student questions during class. Likewise, we harvest common misperception and questions from office hours. These often turn into excellent exam question as well, since they are topics that could confuse a student but that were covered in class.
More advice about creating an exam appears at http://homes.cs.washington.edu/~mernst/advice/exams.html