I did that with my custom truck, I made the wheels spinning, and the whole building I was in spin. so the truck would drive around and around.
Also, if you guys want a cool teleport effect, tie the whole place to a func_rotating and then when your inside, you will of course be spinning with the place, so you wont relize its spinning, then spawn in monsters, and have them spawn out(like in the original hl first part). You see they fall straight down, while the place is spinning, so it makes a tornado type effect. And the monsters spin around in circles before they land... I'm also thinking about doing this for the compo, so don't take my idea!! lol