Google Voice is one of my favorite applications. I use it several times a day. It has transformed the method I use for phone calls. Life is easier now.
Google has now posted a comprehensive list of videos explaining how Google Voice can be tapped to your advantage. The videos may be found at http://googlevoiceblog.blogspot.com/2010/02/google-voice-explained.html or you can watch the first one by clicking on the RUN icon in the middle of the image below.