New Teacher Center with the technical support os Samoo team has developed an external report tool that allows a user without enter into sakai to extract reports from sakai user activities.
It uses some tomcat features (a valvule that stores certain information in a own table) and sakai access to the database to extract all the information.
Very soon we will upload full documentation and source code. It's not a sakai tool, it's a JSP application external to sakai so it's not very difficul to adapt to your needs. To add a new report is "so easy" as add a new jsp file and update the menu.you can do all this changes without stop tomcat.
It's writed for Sakai 2.5.3 but we are going to update it very soon to new versions of sakai.
If someone is interested and can't wait until we update this page, can contact with me for more information: