Want to share? Elecom's 2 in 1 Speakers and Headphones allow you to share your music while on the go. If you're alone, then they function like regular old headphones.
But if you want to project your music, simply plug the earbuds into the speaker and your music can be heard out loud. The quality isn't too great to serve as an instant party, but for impromptu music listening sessions it would be fine.