Ambrosia Software released version 1.0.1 of their iToner Ringtone software for the Mac.
iToner enables you to quickly transfer custom ringtones for your iPhone - without modifying, hacking or having to reset your iPhone. Simply drag and drop your MP3 or AAC audio files on iToner's window, click the Sync button, and you're done! Even better, your ringtones will continue to work with future iPhone OS updates.
iToner 1.0.1 fixes an incompatibility introduced by iTunes 7.4 for custom ringtones on the iPhone.
While there was a seemingly simple way to put ringtones on your iPhone for free, the technique appears to have broken in iTunes 7.4.1 and was never 100% consistent to begin with.
So for those who don't want to deal with that hassle, iToner offers a simple $15 (one time) solution.