After having tried and been disappointed by the Treo Wireless Headset, Scala 500, and two Motorola headsets, I stumbled upon one that is easily the best of the bunch with my Sprint Treo 650. It's called the Southwing SH310. I found it at a Cingular store for $39 before a $10 mail in rebate. Not perfect and not the holy grail or anything but by far the best of the five that I tried and I'm happy with it. May be worth a shot for those of you who are still looking. I use it without the ear loop but instead with the Jabra eargels from Radio Shack, which fit perfectly.