Today most of us have many contact methods and .tel is the ideal way to bring these together in one place. My .tel address means that my contact info is always up to date and available. No more second guessing the most appropriate contact data to give people. No more decisions about what to put on a business card. I've just had some Moo cards printed that just have my .tel address on them; lets people decide how to contact me. If I want to restrict contact methods at any point in time I can just hide them. Some of my contact data is hidden and only available to people who request it, although I've tried not to do this with too much data because it's less user friendly. Access via a mobile device is great because you just click on the number to call or SMS it. No need to re-key and you know it's a current number.
I believe we have only just started to scratch the surface here. As an example, .tel addresses use a common data structure, so in the future it will be possible to just enter someone's .tel address into your handset and call or email them without even knowing their number or email address! A .tel will become a universal contact method whether you're emailing, calling, instant messaging or using a social networking application.