I've been playing with the most wonderful and devious service this morning. It's called Hoax Call, and it lets you prank call people right from your browser. If you're familiar with soundboards, the Flash-powered array of links that play small sound clips from popular movies, you'll feel right at home with Hoax Call. It offers three of these boards that can control, then use to connect you to any number in the U.S., Canada, or the U.K.
Each soundboard scenario has a different theme. The site has launched with just three, one that fakes a radio call, a standard wrong number, and an "annoying eBay buyer" who is attempting to return a computer they got off the auction site. What's neat is that it combines your standard soundboard with VoIP calling, so you can hear your phone call through the computer speakers, then send over each audio clip in near real-time. You can also tweak specific details like your name and the person you're trying to reach so that it can be personalized, lessening the chances of the person hanging up.
All of this is something you were able to do before, although not without a fair bit of effort and some equipment. To do this you'd need a good VoIP application with some sort of proxy, as well as a pair of split headphones to be able to hear what was happening on the other side of the call. This service also provides complete anonymity--there is no special sign-up required; you just need to know the person's number.
To protect call recipients from getting blasted over and over, any number that's been used is barred from being used again for 21 days. These numbers are saved in a temporary database during that time, then cleared until used again. You can also add your number to the service's block list which will keep it from being used entirely.
Hoax Call is completely free, although the creators say they're adding a premium service later on that will add additional scenarios. If they're smart they'll add a recording tool that lets users share their calls, too.