I guess there are military aptitude tests. And I am curious about which big companies administer an undisguised IQ test to applicants.

It appears that an IQ test can be administered if it can be argued that a certain score is required to do the job, and the test is not simply a way to discriminate. It sounds like a court case waiting to happen though: how does one prove what score is required? Easier if your defense is "we never administered an IQ test, tour honor".