I know I can do this via javascript, but it would be very helpful to have a UI in the User Task Form properties where I can set values to variables when an Action Button is pressed.

So if the Submit button is pressed I could set a status variable to a value or set it to something else if the Reject button is pressed instead.

That way you could say more easily customize the email that goes out when a task gets assigned.  Actually it would be handy for a number of reasons.