Discovered this a few days ago. If you use ABC at all, this is the best I have seen, and it is free!
It will play a tune... in any of a few dozen instrument modes, display the melody on a staff, allow speed & volume alteration, do searches, allow new tunes to be created....and many other tricks.

   PC only, of course...sorry. (Page is in both French & English)

http://abc.stalikez.info/abcex.php

I had a file of 260 shanty tunes, and it loaded them instantly and played them flawlessly. Now I am going to retrieve the ABC files from Bruce Olson's collection! (in Mudcat's drop-down menu)