[whpalmer4]

If you have a list of actions which are potential candidates to be promoted to "due today", select them all by clicking on one and cmd-clicking on the others to build up the selection (or shift-clicking if you've got a contiguous list), then bring up the inspector and set the due date to today. Setting the due date on the enclosing project will also rapidly set a bunch of items to have the same due date. Note that changing the due date on the project won't change the due date recorded in the enclosed actions, but they will be treated as if they are due if the project is due.