Has anyone used a heart rate monitor that didn't require a strap? Reebok makes one:
Reebok (http://store.reebok.com/product/index.jsp?productId=1432174&cp=1320288.851740&clickid=hmp_geardrop_8&parentPage=family)

Mio and Impulse also make a few:
Mio and Impulse (http://store.yahoo.com/heartpacers/mio.html)

I would much prefer one of these, but I'm wondering how accurate they are. I think they all work by having you place two fingers on the watch face for a short amount of time.
-neckowi