How do I make in FCP 7 that effect where a spotlight seems to shine from behind text as it moves from one side to the other (with rays of light piercing through the text)? I've done this before but now can't remember how I did it.

Trapcode Shine is probably the easiest way.

If you upgraded to FCP 7 from FCP 6 with Livetype, there's a ready built preset in there. You can install Livetype direct from the FCP 6 disks.