JetAudio (free download) from click here is listed as being able to play M3U files.
I have been using this multi format player for quite some time. Although I don't have any M3U files it has never failed me on anything else I have thrown at it. You may have to go into preferences and set it up though. Do that by going in to Preferences, File Type Association and in the right window click on Check All, Update and then OK. It should now play anything.