Students can review and comment on each other’s work with Google docs, which offers tools for side bar comments and also a ‘suggesting’ mode that allows them to propose revisions to prose, etc. If you expect, for instance, students to save drafts (with comments) it will be a good idea to make periodic Word versions (which preserve all comments) for further reference.
Pros: Free, extensive editing tools means that drafts and revisions can easily be saved as Word or PDF documents with full apparatus or special symbols and formatting.
Cons: Bryn Mawr students will need to sign up for Google accounts and they will need to have user names you can recoginze if they are commenting on drafts or other documents. If student authors are too quick to “accept” suggestions or “resolve” comments it might be difficult to track the process of review and revision.