I had to use the left-handed scissors while making things in kindergarten. On the first day of each school year, I would make sure to sit at a desk that had the arm part on the left side. These desks were harder to come by in high school, so I eventually just got used to sitting in a right-handed one (when taking tests, I would sit facing the right a bit so that my left arm could be supported at least somewhat by the top portion of the desk).
In junior high, my father wanted me to take up golfing, so got me a set of left-handed ones. Turned out that I'm right-handed when it comes to golf (same for bowling, baseball, foosball, etc.) I can use a computer mouse with either hand, though I favor the right.
What percentage of the population is left-handed? Approximately 7 to 10. It's more common in males than females. A recent book called "Right Hand, Left Hand" argues that the proportion of left-handers is rising and left-handed people as a group have historically produced an above-average quota of high achievers. The author says that left-handers' brains are structured differently in a way that widens their range of abilities.
Three of the last four Presidents have been left-handed (W. being the exception). Both Obama and McCain are also Southpaws. Other famous lefties: Ben Franklin, Thomas Jefferson, Winston Churchill, Mark Twain, Aristotle, Charlemagne, Julius Caesar, Paul McCartney, Michelangelo, Leonardo DaVinci, Jim Carrey, Tom Cruise, Morgan Freeman, Nicole Kidman, Robert Redford, Julia Roberts, Robert DeNiro, Brad Pitt, Angelina Jolie, Keanu Reeves, Jerry Seinfeld, Sylvester Stallone, Bruce Willis, Celine Dion, Jimi Hendrix, Sting, David Letterman, Jay Leno, Babe Ruth, Greg Louganis, Mark Spitz, Bruce Jenner, Dorothy Hamill, Larry Bird, Jimmy Conners, John McEnroe, Henry Ford, Bill Gates, Colin Powell, Albert Einstein, and Oprah.