One of the most personal things about your phone is what ringtone (and with Android) what notification sound you have. Using a program called RingDroid, it is possible to create custom ringtones and notification sounds from music you already own directly on your Android phone. Follow these steps and you will be rocking in no time:
1. Download RingDroid from the Market (Market | AppBrain).
2. Start the app and either scroll to find a song or search for it and click on it.
3. You will see the editing screen (as above). Here you will want to drag the start/stop markers and make a clip under 30 seconds (ringtone) or just a few seconds (notification).
4. When you are satisfied, hit Menu > Save or the little file icon in the bottom row.
5. Now you will select what type you are making. Choose between ringtone, notification, alarm, or music. Also, you can create a custom name.
6. Hit "save" and it will ask you if you want to make your song the default ringtone/notification/alarm. If you choose no, you can always go back into your notification or ringtone selector under Menu > Settings > Sounds & display and select what you want.
RingDroid is a great piece of software, and should work with any non-DRMed music file. Once created, the clips will be stored in sdcard/media/audio and can be accessed directly with Astro or by mounting your SD card onto your computer.
Via: (Android Central)