Google introduced "Google Voice", a free service to anyone with a Gmail account. What is it you ask? It's a free phone number that can be forwarded to any home phone or cell phone you already own. You can also make calls from your laptop or desktop computer using the Google Voice interface or right from Gmail.
Now you ask, why and what would I do with another phone number? Simple, use it for your side business or as a new personal number that you only want certain contacts to know about. The Google voice number lets you adjust settings to forward to one or more phones, choose when (what time) to forward the calls, and set up a separate voice mail to handle all calls that are not picked up.