I would recommend against "picking sharp or piercing ringtones". I once had a horrific on-call schedule and, like any mammal, I developed a Pavlovian response to the sound of my pager which resembled those door buzzers that retail stores use. Friends of mine told me that I used to jump when I heard them go off.

So realize that whatever that ringtone is you'll associate it with this kind of anger: http://www.jeckels.com/photoDetail?PhotoId=4586&Category...