//Has to go at the top of your file
 #pragma strict
 import System.Collections.Generic;

 //The list of colliders currently inside the trigger
 var TriggerList : List.<Collider> = new List.<Collider>();

 //called when something enters the trigger
 function OnTriggerEnter(other : Collider)
 {
     //if the object is not already in the list
     if(!TriggerList.Contains(other))
     {
         //add the object to the list
         TriggerList.Add(Other);
     }
 }

 //called when something exits the trigger
 function OnTriggerExit(other : Collider)
 {
     //if the object is in the list
     if(TriggerList.Contains(other))
     {
         //remove it from the list
         TriggerList.Remove(Other);
     }
 }