As well as being to state a specific amount of elapsed time before the next action / email to be completed next in a workflow, it would also be useful to be able to specify a date when this is to be completed.

This would be helpful when using these for event management, e.g. to be able to program in a set date one week before the event to send a confirmation email. 

Currently workflows can't be used for events when sign-ups are staggedered.