I'd also recommend asking people for their FIRST name only, and emailing people with a personal email right after they sign up for the beta. Start a conversation, ask them what their problems are, what features they want, etc. Make them feel special, and tell them "Nice idea, why didn't I think of that! I'll try to include that."<p>They're sure to remember you if you do this. You can even do automated email segmentation. If their reply has "Sent from my iPhone", you know you can send launch emails for the iPhone version to these guys. If their reply has "Sent from Droid", send the Android launch emails to them.<p>Starting a conversation also lessens the probability your launch email gets put in spam as well... I'm sure Gmail, Yahoo, etc all have algorithms where if you respond to an email address, any future emails from that email doesn't get marked as spam.