I would recommend giving the user an option like what we have in Opera. A field with Minutes and a field with Seconds so the user can put anything between 0:01 and 59:59 or some such.
If I were to use it in such a fashion (would require me to have two monitors first
) I'd probably set mine to ~5 minutes. But then again, if I were given a choice, I'd probably change it a lot
@Mind: If I do try your utility I'll be sure to give you feedback