DCNH application for Dual-type theory
Probably the unemployment office.
I think that these theories of personality are relevant enough to ideal career placement that they warrant use as a job hunting tool. They are the counter-part to Big 5: Big 5 is not your friend unless you are a manager. Else it is your enemy because it is a means of discriminating between employees. Companies have too many aces already. It's time to balance the field in favor of the employee, by giving them the ability not only to know what they are good at, but the motivation to hone and sharpen their skills to get the jobs that are out there.
Still, I think that employer and employee don't necessarily have to have an adversarial relationship. Why not bring the two together by matching prospective employers with qualified employees?