Recently I discovered a new source of PMP exam sample questions from PMP Prepare. They offer 2 free exams - one full-length (4-hour, 200 question) sample exam and a 10 question mini-exam. You need to follow a simple registration process to gain access. I haven't had a chance to go through all the questions, and cannot comment on the quality. If you have any feedback or comments on the quality of questions, I encourage you to post them here.