Boosting the Cellular Signal, Inside?

Ryan Black asks: "I live in a suburban area where cellular signal strength is not what it should be. I am a Verizon customer, and while they have been courteous in addressing the issue, they have not been able to fix the situation. Is it possible to create a sort of cellular repeater to attach to the roof of my house? The signal outside is acceptable, it just cannot penetrate the walls of the building."