I know that there was a similar thread about Google Voice, some time ago, but it has since been closed.

I just want to make sure that everybody know about this wonderful (and FREE) service!

it is packed with great features that allow you to do the following: know who is calling (even if you don't recognize the number in caller ID) by requiring the caller to state their name, which you then hear before deciding whether to accept the call; record customized voice mail greetings for groups, or even for individual contacts; and set the service to ring vertain phones at certain times, all with just a few clicks of your mouse.

My Google Voice number is the only number that I give out (for both clients and personal use), now.

I recommend that everyone consider using it! The only challenge is in getting all of your contacts to transition to this new number. Google Voice's "Help" section even gives you tip on how to do that!