Professor Messer, CompTIA A+, Network+, Security+, Microsoft Certification Training. CompTIA A+ Essentials (2009 Objectives) assessment tests. A+ practice exams. Here are a number of links to free A+ practice exams, demos, sample questions and quizzes for the CompTIA exams - covering both the A+ Essentials and the A+ Practical Application.
While some of the links might point to resources for older versions of the A+ certification, many of the concepts and questions used then are still relevant today so it's worth doing as many practice questions as you can.