I just bought the Motorola S9 Stereo Headset to use with my Eris. It works pretty darn good. Although I'm having issues with connectivity. Not because of the S9 headphones but with the bluetooth on the Eris.
It's really weird, like everytime the phone shakes when I'm walking the sound cuts out or if I shake or hit the phone lightly the sound gets choppy.
I would love if anyone has experienced that to post here and to let me know if that's normal. If not then I'm back to Verizon to exchange for another Eris.