The "Skyterror" personal delivery system from the Gnomish gearworks can be used in older areas of warcraft with no-fly zones. You can access areas and content that were never supposed to seen using the item.
In this video I cover some of these areas. Some of these normally inaccessible areas have interesting properties for exploiters with gamebreaking potential.
Aside from the places mentioned in the video (isle of quel'danas, isle of thunder and molten front / firelands) the skyterror can also be used in Tol Barad, and the blood elf/Draenei starter zones.