If you're anything like me, you don't take kindly to unexpected visitors. The doorbell is a sign that something has gone terribly wrong, and I may soon be forced to interact with other people. Shhh, just be quiet and they'll probably go away. Okay, maybe you're not exactly like me, but perhaps you want to know who's at the door before you get up. The Ring WiFi doorbell can do that, and it's on sale for $169.99 right now on Amazon.The Ring doorbell is basically a fancy WiFi security camera that happens to have a doorbell built-in. It can be powered with batteries, or wired into your existing doorbell line, if you've got one. Once it's on your WiFi network, you can use the Android (or iOS) app to view the feed and track motion and doorbell rings. It will also push notifications to your phone when the doorbell is used, even if you're not at home.Ring usually costs $200, but it's $170 on Amazon right now. That appears to be the lowest price available. However, that deal is only good on the black model. There is a $3 monthly subscription service to archive video from the doorbell in the cloud, but it still works for line feeds, ringing, and notifications without the sub.Source: Amazon