Google started sending out invites to one of its new services this week, Google Voice. For a detailed list of features of Google Voice check out the about page on Google’s website.
The basic idea is that you can use Google Voice as a single phone number that will ring to your cell phone, home phone and office phone all at the same time (if this is how you configure it). Your voicemails will be stored online just like your Gmail, the voicemails will also be transcribed for you and emailed to you if you want. There are options for SMS as well. The list of features is pretty impressive, I would highly recommend requesting an invite if it interests you.