Another great product acquired by Google - I think they're going to end up taking over the world. Check out Grand Central, a new free service from Google that allows you to register multiple numbers (work, home, mobile) and then gives you 1 phone number for life.
You get voicemail and tons of options like personalized greetings per contact or "CallSwitch" - the option to transfer a call from your home or office phone to your mobile when you are heading out the door. It's in Beta right now, so it seems like there's a slight wait. Leave a comment w/ your email address if you want me to send you an invite and skip the wait.