I use Cool Edit Pro to make mono MP3s for ringtones. I've posted links to download a few.....take a listen and see what you think.
Here's one that rings when my wife calls:
www.need-geek.com/downloads/Brick_House.mp3
....one that rings when one of my girlfriends (or my buddies' girlfriends) calls:
www.need-geek.com/downloads/Gimme3steps.mp3
....one when my good buddy Tony Soprano calls:
www.need-geek.com/downloads/Sopranos.mp3
....my "new mail" notification:
www.need-geek.com/downloads/Ed-GotMail.mp3
....one for you Michigan Fans!!:
www.need-geek.com/downloads/Victors.mp3