Aheadset
Another "modern" classic, the Aheadset allowed manufacturers to skip threading the fork steerer tube , as well as permitting the use of lighter stems. For the user, it means that adjustment can be done with a 5mm allen wrench instead of large specialized wrenches. What's not to like? Well, I'm sure that is discussed in another thread.
Steve in Peoria (and I do have two bikes with Aheadset style headsets)