List of Major League Baseball single-game records: Information from Answers.com
A good list of baseball rare events. There are rare events that take an inning or a whole game to occur. Then there are events that happen with just one pitch. There have been 15 pitches that resulted in an unassisted triple play but only one TP happened without the ball touching the bat. Interestingly, 25 players homered on the first pitch they saw in MLB. But only 7 pitchers surrendered a HR on the first pitch they threw. So, the next time a rookie pitcher makes his debut you'll know what to look for if you want to see history.
One of the rarest pitches you might ever see is ball four of an IBB with the bases loaded. There have been only 6 of them. So, the next time the commercial comes on where the lady says the rarest play in baseball is the unassisted triple play.... she's wrong, it is the "non-batted" triple play.