McGill's Teaching and Learning Services (TLS) has been involved with clickers for several years and has a very useful clicker page.
Why peer discussion improves student performance on in-class concept questions. M. K. Smith, W. B. Wood, W. K. Adams, C. Wieman, J. K. Knight, N. Guild, and T. T. Su. 2009. Science 323: 122-124. DOI 10.1126/science.1165919
Clickers in the large classroom: current research and best-practice tips. J. E. Caldwell. 2007. CBE Life Sciences Education 6(1): 9-20. DOI 10.1187/cbe.06-12-0205
Assessment of the effects of student response systems on student learning and attitudes over a broad range of biology courses. R. W. Preszler, A. Dawe, C. B. Shuster, and M. Shuster. 2007. CBE Life Sciences Education 6(1): 29-41. DOI 10.1187/cbe.06-09-0190