nicotone.com

Hi, I've started making my own ringtones and would like a system that allows visitors to my site to have the ringtones sent to their phones. May be for free, or may be for a charge? What do you guys use to distribute your ringtones? The basic solution I have at the moment is for the users to download the mp3 files and they have to work out how to get it on their phones... not very user friendly! Thanks, any suggestions are really welcome. Nico