Like .mp3 , you can listen online:
.mp3
http://d1.s.hjfile.cn/podcast/20100222/2010022290717093_217.mp3
But I do not want to allow downloading.
How to approach this?
Everything that can be streamed can be downloaded. There is no reliable way to prevent this. Look at all YouTube and Hulu downloaders despite their efforts to prevent them.
You can use the Flash audio player.
http://www.macloo.com/examples/audio_player/
He will simply play the song, but will not allow them to save it. You should always get around, but this is a good start.
You cannot have your own cake and eat it too. If your users can listen to it, they can write it to a file. You can make this less convenient by using the streaming protocol, but a specific user can still capture the audio stream and save it in a file.
You can encode mp3 to swf . Users can download swf but cannot download it on their ipod if this bothers you.
(Link to a commercial product that I found using Google, but there are probably free alternatives)