1. Santa Calls from Gmail : As mentioned on Google Blog "If you or your family members have a special request for Santa, you can call Sanata from Gmail and leave him a message at his Google Voice number: 855-34-SANTA. Santa won't be able to return messages himself — it’s a busy time of year for him—but he's promised to keep us up to date on happenings in the North Pole day by day."
2. Send a call from Santa : sendacallfromsanta.com is a service by Google itself. You ca create a unique and customized message and send it from Santa to anyone you know, from your nieces and nephews to old college friends, over the phone (to U.S. numbers only). SendacallfromSanta (by Gmail) looks like a great service to me. If you are in US then, this is a must try!
3. Christmas Dialer : christmasdialer.com is also offering a free call from North Pole. You can make this holiday special for any child with a merry phone call from Santa!
4. Santa Dial : santadial.com is also offering similar service. You can send 3 santa calls per day.
Please share your Santa Claus user experience.