Huge scary bug. I have no idea what kind of bug it is. All I know is that it's the only time I've seen one & it was HUGE.
Update 03/03/2008
From the Placerita Caynon Web Site I've found out this about this monster.... "This is a wasp that captures tarantulas, stings and paralyzes them, lays an egg inside of them, and then the baby wasp eats its way through the paralyzed spiders body, saving the vital organs for last so that the tarantula lives as long as possible"

www.insectidentification.org/