ArrivedOK sends flight arrival info to Twitter, blogs, email, and SMS
What ArrivedOK does is track your information and send out alerts to let people know when you're safe and sound. You just visit the web site, enter your flight information and a list of people you want to send email or SMS notifications to. You can also post updates to your blog or Twitter.
Now here comes the neat part. When your flight lands, you turn on your cellphone and ArrivedOK will check the wireless network and see that your phone is on. Then it'll send the signals. This way people will know that you arrived OK, and not just that the plane landed, which is the only information they would get if ArrivedOK depended on flight information from airlines or airports.
Of course, I suppose it's possible that someone could find your phone and turn it on after you were smacked in the head by a food cart and knocked unconscience in mid-flight, thus notifying your friends and family that you arrived OK when in fact you've been rushed to a hospital. But really, what are the odds of that?
ArrivedOK is free while in beta.