Dock-n-Talk from PhoneLabs is a great idea. You take a normal cell phone, attach it to the Dock-n-Talk box, and plug the Dock-n-Talk box into a phone outlet in your home. Now, when you pick up any other "normal" phone in your house and dial a number, the call goes out through your cell phone. When calls come in on your cell phone, all the normal phones in your home ring.
What this means is that you no longer need an account with a "land-line" phone company to have phone service in your home. All you need is a single cell phone account, and it can handle both your home and your mobile needs.
For more information, visit the PhoneLabs Web site.