Jaxtr launched a phone application that connects people at social networks and blogs without needing to download a desktop application. Basically you put in your phone number and the application links you with the number they have on record of the blogger or other social networker.
An example can be seen on the Jaxtr blog.
LinkedIn co-founder Konstantin Guericke has joined the Jaxtr team. Guericke was vice president of marketing at the social-networking site for professionals, and his experience in the space should prove invaluable to Jaxtr.
People connect by clicking on Jaxtr application on profiles at LinkedIn or any of a large number of social networking sites that are adopting the application. Jaxtr supports MySpace, LinkedIn, Tagged, Friendster, Hi5, Tagged, Xanga, and Blogger.
Users click on a Jaxtr link, enter a phone number, and the two Jaxtr users will be connected through a special number assigned by Jaxtr.
I tried it at their blog and was forwarded to a voicemail at Jaxtr. It could be a very handy tool.