eTunes (i.e. easyTunes) is a small application that allows even non-professional musicians to create and play their own tunes. In fact it is enough to click the piano-keys and eTunes will take care to code your inputs for the right output.
eTunes' songs can be converted into audio-files (MP3/AIFF/WAV) to be played by other audio applications (ex. iTunes), or may be used as Ringtones for cellphones (for ringtones, make sure you first read the eTunes Help file).