The Calibrated Peer Review (CPR) program is a free Web-based program available at: http://cpr.molsci.ucla.edu/ . This program allows students to write about course topics without greatly increasing faculty workload. Students are trained on the peer-review process and are expected to provide feedback to classmates. Faculty members have access to all written assignments and can monitor progress.
Faculty members design a writing assignment on the site. Students compose a written response to the assignment. Students work through a tutorial on peer review and must score at a certain level on the calibration exercises. Successful students then review the work of classmates (authors and evaluators are anonymous). Instructors can see all submissions. Students then review their own assignment according to the same standards. Students and the instructor receive a performance report.
Read more about CPR at: http://www.educause.edu/ir/library/pdf/ELI5002.pdf