Samsung SCH-U550

I haven't tried it (and really don't recommend it as I've seen bitpim fry phones before), but you can save a trimmed mp3 file on a memory card in the my_sounds folder, then send the sound as an MMS message to yourself and save as a ringtone. I use a program called Audacity to trim down the mp3 file to a 20-30 sec clip and then save it that way. Kinda sucks compared to how easy it was on older samsungs, but it works.