I will be 17 weeks tomorrow and my doppler arrived in the mail today. It's called AngelSounds and I REALLY can hear her heartbeat and swooshes as she moves. I've been feeling little "popcorn" sensations for about a week but now I have "swooshes" to go with it! It's called a Jumper and you can hear the heatbeat as early as 12 weeks.
NOTE: This is not BebeSounds Prenatal Heart Listener(used during 3rd trimester). This is a fetal doppler/heart rate monitor similar to the kind used in doctor's offices.