Currently you can run a Contact Activity since a specified date for Contact fields, Notes, Opportunities, Histories and Activities that provides a list of all contacts that have any of the aforesaid actions but not what those actions were. You can run Notes and History Report and/or an Edit Lookup but none seem to give a complete audit trail of any changes made in the database over a specified time period and to be able to filter this by type of action taken (e.g. histories, opportunities) and/or changes made (e.g. database changes) and by all or any user.
A filterable audit trail report for any type of action or change made in the database would enable managers who have been away to run this report for set dates and see all the actions and changes made in their absence by all or any user so they can keep up to date with what has happened.