Peer assessment is frequently used to provide feedback during the completion of a project, particularly in large classes. There are several varieties of peer assessment including having students provide peer feedback in the early phases of a project, using peer feedback to determine a final grade on an assignment, and granting credit corresponding to the level of effort and usefulness of comments made on peer reviews.
Within an online course you will have the option of using a built-in peer assessment tool. With such a tool you will be able to set up an assignment to automatically distribute students a specified number of their peers submissions, and provided rubrics to complete. In order for peer assessment to be most effective, developing a detailed a rubric or guide and teaching students how to apply them is essential.