You can also pick up one of these for around 15$ If your external speaker isnt loud enough. I've used one before, they work well and are small enough to hardly notice while in your goggle pocket.

I have the iHome iHM60GT Rechargeable Mini Speaker, sound is pretty good but it wore out in about 2 months, currently looking to see if I can get it repaired under warranty. It was pretty cheap, about $15?

I would pick something different, cant really recommend based on build quality, but sound quality appearebntly they are better than the X Mini II, check out the video review http://www.amazon.com/gp/product/B004OA733E/ref=oh_details_o05_s00_i02

If you want the best apparently it's these at almost 3x the price http://www.amazon.com/Altec-Lansing-Ultraportable-Speaker-Players/dp/B001ELK2NY/ref=cm_cr_dp_asin_lnk

check out