Are you looking for music listening also? (A2DP)
or just taking calls?
I have a Jawbone Prime that's great.
I pair it with my Droid.
There's this new one that's supposed to be annouced at CES very soon. It looks really cool and has some great features.
http://www.engadget.com/2010/01/04/spracht-aura-hq-bluetooth-headset-boasts-dual-mics-equalizer-an/
Yeah that looks super hot. My two favorite are the Jawbone:
http://us.jawbone.com/
And the BlueAnt z9: (z9i now, I guess)
http://www.myblueant.com/products/headsets/z9i/index.php
I will say, I have a jawbone prime after losing my 2nd gen jawbone (the new jawbone i think it was called?). I have to say its MUCH better with reception, as well as clarity. loving it.
EDIT: just for reference, I used it with my verizon XV6800, now I use it with my nokia N900.
BlueAnt z9i. I got it and it picks up my voice a lot better than my old Motorola.