How To Get A Free US or UK Phone Number
In addition to saving on long distance calls, having a real geographic phone number to forward to your VOIP software or home phone/cell number is like having a second (or third, or fourth etc) phone line. You can use it as a throw-away phone number to give to potentially dodgy people - the same way you would use a random Hotmail address for registering on dodgy sites...
This article lists a few places where you can get free US or UK incoming numbers, as well as more fun ways to use such numbers.