There's a very interesting new service in beta from a company called Jaxtr. It allows you to link your phone to pages in your social networks, your email signature, your blog etc. so that anyone worldwide can call you with just a click of the mouse. Your phone number is kept private, and you don't need to download or install any client software.
This gives you the ability to have a "virtual" phone number that you can link to your existing phone numbers or future phone numbers when they change. Should be quite interesting if they can pull it off and provide an excellent user experience.
