Although I was previously a wired headset kind of guy, I recently caved way to using Bluetooth headsets for the added flexibility of being cord free. After a little bit of research, I landed on the Logitech H800, which after a month's use is not bad. It has an on-ear fit and is relatively comfortable. Battery life is decent at around 5 hours, but I would mind more juice coming from a relatively large headset. The one drawback is the microphone, especially when I'm outdoors - it picks up too much wind noise and renders conversations with people impossible.
If other folks have experience with other Bluetooth headsets, especially for phone conversations, we would love to hear your experience and recommendations.