Google has just announced that starting today, U.S. based Gmail users will now be able to place and receive phone calls directly from the Gmail interface. Calls placed to U.S. and Canadian-based numbers are free, and if you need to make international calls, the rates are extremely cheap.
I signed up for a Google Voice number about a year ago when I needed a new business line that I could have transferred to my home office or to my cell phone. The added bonus of this type of business phone line is that the voice mail is transcribed and sent through email/text and stored online for review online.
Check it out: