Jangl allows you to exchange IDs to strangers to allow them to call you without actually revealing your phone number. The recipient of your Jangl ID plugs the ID into Jangl, which generates a phone number that routes to your regular phone. You can then call this same number to reach the other party. All this goes on without either side exchanging real phone numbers. Simple and effective.
Why would you use this? Two examples we can think of are dating and online eBay sales. If you don't want to give away your home phone to strangers, Jangl will protect your privacy for free. You can even route Jangl calls to any phone, whether it's your cellphone, landline or VoIP number.
Product Page [Jangl]
Press Release [Yahoo]