A new US-based phone service is doing the rounds on the blogs. GrandCentral allows you to choose a single, unified phone number to replace all your individual phone numbers (home, work, cell, yacht, private jet ...).
When someone calls this unified number, all your phones ring at once. Depending on your personality type, I guess you'll either find this hugely useful, or it will turn you into a twitching, hunted wreck.
The service has a bunch of other features, as detailed in an article by David Pogue in the New York Times last week.
One Number That Will Ring All Your Phones - David Pogue
Tim O'Reilly on Pogue's article