i4i's x4o (XML for Office) allows users to review and comment on XML documents in the familiar Microsoft Word interface. To the reviewer, it is simply a Microsoft Word document. Reviewers are prevented from changing the content or the XML structure - they are restricted to adding Microsoft Word comments to the document. x4o also provides track changes functionality.
In cases where there are many reviewers, manually reconciling comments and changes is a time consuming, expensive, and error prone task. ALiCE (i4i's Authoring Lifecycle Collaboration Environment) eliminates this problem. ALiCE allows you to consolidate comments and content changes from many drafts of a document into a new version of the document. Using an editing tool, such as i4i's x4o, changes and comments can be accepted/rejected or deleted accordingly.
Click here for more information on ALiCE.
Click here for more information on x4o.