I’ve had Google Voice for awhile now, and I have to say it is the best service I have seen from Google. It is still in BETA, so you need an invite to get in.
Some of the features I like is how you can text and call people straight from the control panel and how you can also block spammers or other people who you don’t want to get calls from. Google defiantly has a strong architecture behind Google Voice. their voice mail feature is very handy with the transcripts and I can download the voice mail so I can use it with my podcast questions. All around, once Google Voice comes out of beta it is the application to get.