The 1.1.2 update to the iPhone quietly added the ability to add free custom ringtones to the iPhone. The ringtones can be made from any (non-DRM'd) ACC file on your computer. I discovered this accidentally while downloading SoundSource from Rogue Amoeba. They had a new freebie called MakeiPhoneRingtone. Just drop an ACC sound file under 40 seconds onto the app and it puts it in iTunes, ready to be downloaded to the iPhone the next time you sync. Works like a charm.