Social Engineering [SE from now on] is an everyday technique used by people who may not even use a computer. SE within the hacking community got more attention drawn to it when Kevin Mitnick was arrested and I think you should read a few of his books. He also had a few films made about him, one was bullshit from Miramax that could have damaged Kevin and he may have never got out;the other was made by the 2600 crew...a true documentary of the events.
Johnny Long is also a good social engineer, very good indeed. You should seriously watch his DefCon called No-Tech Hacking. It's a very interesting and funny conference, seriously watch it.
SE has no limit, you could buy a Bell or British Telecom linesman uniform on eBay or design one. Then buy or design one of those engineering tents with red and white stripes. After that you could pose as an employee, work on the street/roads, then after that you go to jail . Joking aside, if you have a good imagination you can do anything with good social engineering skills. I would like to type a lot more, but its getting late.