Spotted via Mac Rumors, you can convert your iTunes files for free into ringtones for your iPhone.
How? Really simple and I did it.
Convert your ACC iTunes file to a M4R file (just duplicate the source music file, change the extension to .m4r) and then readd that file to iTunes.
I personally opened a file in Apple QuickTime, then clicked export to to ipod and renamed it there. Then I double clicked on the file and presto, I was able to add it to my Ringtones.
I just did this for the iPhone commercial theme song. I will have no patience to make other songs into ringtones.
But nice to know this is a way to do it.