Go Straight To Voicemail
Regardless of your feelings on voicemail (and I think I've made mine pretty clear), there are still times when leaving a message for someone is preferable to actually talking to them. (Think: checking in late afternoon with the boss, dealing with cantankerous clients, reaching someone you know is in a meeting, etc.)
So now there's a way to get straight into someone's voicemail without actually talking to them or having their phone ring. It's called Slydial. Here's how it works: Dial (267)759-3425. At the prompt, dial the person you want to reach. After you listen to a short ad, you can leave your message.
As several people in the Slashdot forum explain, there are lots of ways to do this without having to use Slydial, but it varies depending on your service provider. And in my experience with Slydial, I got a busy signal more than half the time, which was annoying. (Though that will probably go away as the initial wave of publicity passes.)
But overall, it's a useful service.
(Photo via Silas216)