The three virtues of a programmer: Laziness, Impatience, and Hubris. – Larry Wall
This is actually a very useful actor if you want "scripted events" of sorts. You basically just set the delay (under the TimedTrigger tab of the actor properties), tell it whether or not you want it to repeat (bRepeating in the same tab), and then hook it up with the actors you want to trigger just like you would with any other trigger. When you start the map, the trigger will count down for however many seconds you set the delay to and then activate just like any other trigger. This is useful for having ships take off, triggering explosions, looping movers, SmokeGenerator objects, etc. Unfortunately InitialState is ignored, so the time delay is always measured from game start and never from activating the trigger.
See Trigger Systems for examples.
The TimedTrigger class isn't available in UT2003, but see TimedTrigger for a custom class.