I was lucky have got into GrandCentral a what it seems a long time ago and invited a bunch of people who were close to me. They are ever so thankful to me and now even more so because, under Google Voice, operations and capabilities have multiplied, like receive SMS messages via email, transcribed voicemail and the option to change your Google Voice number if you ever want to!
Now if you are a Google Voice User, you can invite your friends and family to share this wonderful experience, which I call the best thing that could ever happen to telephony, so much so that the likes of AT&T are hell bent on stopping Google Voice or slowing down it. AT&T even called the kettle black by complaining to FCC about Google Voice.
But one thing for sure, thanks to Google Voice, now I have a phone number that no phone company can touch, other than sending and recieving calls from it.
Google Voice Blog: Invite a friend to Google Voice