I am experimenting with using Wetpaint Wikis as online classrooms for my students, with pages that outline lesson objectives and summaries, assessment criteria, examples of work, resources, collaborative research projectsetc. I wanted to find a way of putting my cumulative assessment sheets online so that they could be viewed and written on by myself and the individual student, and by parents when required, but so that the sheets weren't not viewable by the entire class.
After posting on a forum for educators I took suggestions from several people and came up with the following method using GoogleDocs as the host for the assessment sheets, with links to those documents from the wiki.
Step by step the process is:

• Go to GoogleDocs and set up an account - you then have webspace to store documents of all kinds, in folders, just like you would on your hard drive or flash drive, however, you can also give others access to the documents. There is an introductory video to GoogleDocs below.
  
• In a word processor (Word, Open Office, Symphony, etc) set up a template in which you will enter your comments and grades.
• Save this template to GoogleDocs - once for each student, with the doc renamed each time to bear the name of the student.
• You can then invite them to view or contribute to the document using their email address. If you don't trust them not to alter your grades you can invite them to view only. I invite them to contribute so that they can add their own self-assessment to my comments and set their own targets for improvement.
• On your wiki set up an 'Assessment Links' page. Make a list of the students' names and hyperlink each one to the URL of their personal GoogleDoc.
• The students then need to set up a GoogleDocs account, which will give them access to the assessment sheet. When they click on their name on the 'Assessment Links' page on the wiki it takes them directly to it... and they can only access their own.