I've found on my skyrockett that if I add an mp3 to the directory mnt/sdcard/external_sd/media/audio/ringtones it's found by my phone. I'm not fond of this "internal"/external sd thing but since when I had to do a hard reset to make ICS take, as downloading it from samsung made it modify the root directory, and doing so didn't cause me to lose any files in the mnt/sdcard directory I think I'll live with it. Hope this helps, I know the suggestions on here helped me get a ringtone back I wanted, lost it with ICS and had to record off older phone. You'd think google would just have a spot in the ringtone list that allows you to search for an audio file, maybe someday.