This was just sent to me and I have just started to try it out. A company has setup a service that will give you a local number and it then forwards it to up to 6 phones at the same time when someone calls allowing you to answer on whatever line you want. It has a bunch of other features like voice mail and all as well.
The best part is that it is in beta at the moment so the service is free for now. If you want a number that will never change and can be forwarded anywhere in the U.S. its worth a try.
http://www.grandcentral.com
Just thought I would pass it along in case someone wanted to try it out while it is still free.
Todd