Twitter made the leap this year from tech-world phenom to mainstream brand. The microblogging platform allows users to write and disseminate short messages, known as tweets, that are capped at 140 characters. More than three million users worldwide have set up accounts, and nearly every major news event this year marked a surge in traffic. Twitter CEO Evan Williams posted updates on the company's progress -- and his own daily habits -- constantly (see "A Year in Tweets," right). So did Barack Obama and Dave Matthews. In Egypt, an American grad student used Twitter to alert his colleagues of his arrest for photographing an antigovernment rally; the U.S. Embassy was called, and he was released the following day. As Inc. observed in a March profile of Williams, the company (which raised $15 million in 2008) hasn't figured out how to make money. Still, few businesses can claim to be as much a part of the Zeitgeist. …In one of the odder controversies of the year, Pinkberry, the fast-growing Los Angeles frozen-yogurt chain, quelled a long-running controversy about whether its product contained enough live and active bacterial cultures to be considered bona fide yogurt. In April, the company settled a lawsuit for legal fees plus $750,000, paid to two charities, brought by a woman who charged that the company erroneously represented its product as "all natural" and "yogurt." Along with the settlement, Pinkberry modified its recipe to earn the imprimatur of the National Yogurt Association.…The Wall Street bailout was intended to bring stability to the precarious world financial system. It also saved a much smaller company that would seem to have little connection to the crisis. An earmark included in the bill to obtain its passage eliminated the federal tax on kiddie arrows used by Boy Scouts and grade school students. Rose City Archery in Myrtle Point, Oregon, is among the handful of businesses that will benefit from the provision. CEO Jerry Dishion says he received a flood of vitriolic phone calls after the earmark was reported in the press. But he contends that the tax break merely gives him a chance to win back the 60 percent of sales the company lost in 2004, when the tax was first imposed. "We're not some big, nasty corporation," Dishion says. "We're really just a hole in the wall in Oregon."…The NBC series The Celebrity Apprentice, which aired from January through March, featured a screwball cast of stars, including Carol Alt, Marilu Henner, and Stephen Baldwin. But it was Kiss's Gene Simmons who stole the show and displayed the most resourcefulness. In one episode, he came up with an idea that sold $52,000 worth of hot dogs. Simmons was subsequently fired by Donald Trump after losing a challenge that involved marketing color printers. "I think we succeeded, and the client didn't recognize it," Simmons said. …Amid the festivities of the Beijing Olympics, tragedy struck one American company: On the day after the opening ceremonies, Todd Bachman, the CEO of Bachman's, a floral and garden center in Minnesota, was fatally stabbed in Beijing by a deranged man who then committed suicide. The U.S. men's Olympic volleyball team, which Bachman's son-in-law coaches, won the gold medal. …To quell speculation that his pancreatic cancer, first diagnosed in 2003, had recurred, Steve Jobs paid homage to Mark Twain in a speech in September, including in his presentation a slide that read, "The reports of my death are greatly exaggerated." The audience cheered, but concerns persisted. In October, Apple (NASDAQ:AAPL) stock fell following a false report that Jobs had suffered a heart attack.…It was a terrible year for initial public offerings of stock. Rackspace (NYSE:RAX), the San Antonio -- based Web hosting company, made its debut (through a Google-like Dutch auction) on the New York Stock Exchange. The August 8 IPO did not go well, however, with the stock opening 20 percent below the listing price on the first day.…The Comeback Kid Award for 2008 goes to Netscape co-founder Marc Andreessen. A decade after he seemingly lost the Browser Wars, Andreessen's social networking company, Ning, is one of the hottest start-ups around. Having raised $60 million in April, Andreessen wrote that he would use the money to fund additional growth and "to make sure we have plenty of firepower to survive the oncoming nuclear winter."