Web base contact management has been becoming more and more popular in last few years. The advantages are obvious. I am not going to discuss them here.
Though there are still some criticisms against it, saying privacy and reliability etc., however, web base contact management is still the most attractive solution for metro people who "always" have reliable and constant internet connections.
However, small or large disasters do strikes occasionally. Plan B. Do you have a handy plan B for contact management?
Some prefer the PC desktop/notebook as a hub for all contact info and sync selected data to other platforms/programs. They won't be effected if the internet connection to the Web base contact management site is down. You still can access phone numbers and ring people. But when power is down, computer is useless. With laptop and UPS, things will become just a bit better.
Mobile phone / PDA is handy , though they are not good candidates to be hub of contact info. I am sure that everyone will naturally store emergency numbers and frequently used numbers in phone. Yes, you have already got yourself a plan B.
When you are busy having phone talks during power outage, the battery of your mobile phone become flat. You then can not access the address book on the mobile phone in order to ring through land line which is generally not effected by power outage. So, a low tech solution will come to rescue, if you have implemented such solution: printing those contact phone numbers on paper, one copy at home, and another copy in your wallet.