I know these get mixed reviews, but I think these are great:

http://www.amazon.com/Motorola-S10-HD-Bluetooth-Headphones-Packaging/dp/B004BHCSQC

I sweat a lot so I like the fact that they are made for running. Also, I use my iphone in a Lifeproof case with the Armband so the bluetooth functionality is crucial.

I love my Motorola S10 HD Headset