For those of you that own an iPhone, here's a cool little hack that allows you to get your own music onto your iPhone. To get this to work, I hear you only need to rename an AAC track to .M4R, then double click it and iTunes will automagically load it into iTunes for you. Next time you plug in your iPhone to sync up, just check off the song in the Ringtones tab and voila, instant tone gratification!

Not sure if someone has shared this, but like every other audio "distinction" in iTunes, "ringtones" are no different. They are AAC files with a special name. In this case, the extension is "M4R".

1. To add a ringtone to your iPhone, using Windows Explorer or the Finder just duplicate and rename any AAC file to be "M4R", then double-click on it. This file will be added to your iTunes library automatically.
2. Now, click on your iPhone in iTunes, and go to the ringtone section. You should now see your new ringtone. If you want to be sure about the sync, feel free to click "selected ringtones" and check off the file explicitly, though this shouldn't be required.
3. Now SYNC your phone. You're Done!

Note: Apple did already release a new version of iTunes last night, 7.4.1, and I tested to see if said update "fixes" the ringtone-renaming hack. Unfortunately, the hack did not continue to work just fine for me.