Soundclick doesn't require any kind of registration just to listen and it works on most browsers.

Soundcloud on the other hand no longer works for anyone using XP and IE 8.

I'm not familiar with Box. Personally I don't like anything where I have to download or "run" a temp file to hear a song.

There was a recent discussion on this in the off topic forum started by Eddie, I think the thread is titled "Song Repository".

Whatever you choose, it's best to post one song at a time. Hope that helps.