I would recommend ServiceDesk Plus by ManageEngine, I have used it now at two different companies and highly rate it. ManageEngine now offer a cloud option which is our preference.
ServiceDesk Plus
There is a brilliant book by the king of Social Engineering called "The Art Of Deception : Controlling the human side of security"
i have this book on my iphone it has loads of different real world scenarios.
Also be sure to check out Kevin Mitnick.