I've been using SplashID by Handango for years. I've had it on my Palm Treo and Centro. It is available for the Droid and works great! The app is available through the Android Market for the Droid or you can get the Droid app and desktop app (PC or MAC) through Handango. The two apps are $39.95. A really nice feature is that you can synch your computer with the Droid over a WiFi connection.