The word for the day for July 16, 2007 is "ringmaster" — noun : one in charge of performances in a ring (as of a circus); broadly : a supervisor or moderator especially of a performance or presentation <the ringmaster of a talk show>.
We went to the Air Show at the local Air Force Base this weekend. They had an exhibition by the Blue Angels flying team. At times it seemed there was no way for them to avoid hitting one another—truly hair-raising for the audience. We were just close enough to the viewing stand to hear the occasional phrase from the announcer, who would state the approximate speed of the planes—"in excess of 500 mph"—for nearly every pass.
As one of the main functions of the announcers at these spectacles is to enhance the thrill, I'm just as happy we were not sitting in the stands to hear the whole spiel. As it was at least 100°F on the concourse, we sat in the scant shade of one of the concession booths and tried to keep cool. I sometimes wonder if the Roman Coliseum had announcers to hype the contestants. "Next we have a match between Brutus Ginormeous, who has won 49 matches against gladiators, lions and wolves, against the Beast from the Uttermost East. This Beast is so savage it will attack even the mighty elephant. Let's hear it for Brutus!"
