Along the lines of tracking the revisions to Sales Orders, I have also had requests for some sort of password control limiting who can change a Sales Order.  
 
One approach would be to first have a default setting to turn the whole thing on or off so people woh don't want the control don't have to mess with it.  Then, if the default were set to control SO Revisions, the Entered By field in the Sales Order would become a required field and be validated against the Contact Manager Rep fields (which have passwords).  Once the SO is saved, any changes to the SO would require entry of the password for the Rep who created the order.
 
Comments and Feedback please!