If you've ever had the need to rearrange the order of subtasks, you know how painful this can be. Lots and lots of page reloads...one for each position you want it to move. I just finished moving a 10th item in a subtask list to the 2nd; stepping through 8 screens to accomplish that goal took about 3 minutes. Ugh.
Seems like the perfect opportunity for some AJAX order arrangement.