Does anyone have a recommendation for a monaural bluetooth headset suitable for the gym?

I love my Backbeat 2 Go, but I like to just use one earphone so the other ear is open to the environment. That leaves the other earbud to flop around on its cord, no matter how I try to secure it.

So I guess a regular monaural BT phone headset with decent music reproduction would work, one that will stay in during exercise.