Turn Any MP3 into an iPhone Ringtone

http://www.pcworld.com/article/156234/turn_any_mp3_into_an_iphone_ringtone.html

 Turn Any MP3 into an iPhone Ringtone

1. Start iTunes and find the song you want to convert. (It must be an MP3.)
2. Right-click the song and choose Get Info.
3. Click the Options tab.
4. Check the Start Time and Stop Time boxes, then enter times for each (no more than 30 seconds apart, the maximum length for a ringtone). I used 0:00 and 0:30, respectively, as "Spit It Out" has a perfect ascending lead-in.
5. Click OK, then right-click the song again and choose Create AAC Version. You should immediately see a new 30-second version of the song.  (If it says MP3, you need to change your import/export preferences to AAC).
6. Drag that version out of iTunes and into the folder of your choice. (I used e:\media center\ringtones\iphone)
7. Delete the 30-second version from iTunes and undo the Start Time/Stop Time changes to the original.
8. Open the folder containing the 30-second AAC file you dragged out of iTunes, then change the file extension from .m4a to .m4r. Double-click it and it immediately gets added to iTunes' ringtone library.
9. Finally, sync your iPhone. When it's done, you can head into the settings and select your new ringtone.
10. Not syncing?  Make sure you have sync turned on the Ringtones  / Tones.  
11. Put your AAC preference back to MP3 if you had to change it above.

That's all there is to it!

If your phone can play WAV files, like most Sony Ericson's, it's a piece of cake to create a PREVIEW file in MediaMonkey (keep it under 30 seconds) and copy the new files to your phone.