In the original Unreal Tournament, the shock rifle was really the weapon of the discerning fragger. Using the shock-combo, where you first press the alternate-fire and a ball of slow-moving energy starts traveling towards your soon-to-be-shocked opponent, and then "explode" it with the laser-like primary-fire once the ball is nearly there. The effect was that anyone within a reasonable distance of the explosion would be more or less vaporized. Great for defense and to get that enemy flag-carrier coming around the corner.
Sadly, the range and damage of this weapon have been reduced in the recent versions, but it is still fun to go back and break in some newbs in UT!