Like no social media platform since Facebook, Twitter—a "microblogging" service people can use to broadcast 140-character messages—has captured the fascination of the worldwide media, the public, and even the rarefied world of celebrities. While the number of actual twitterers remains relatively small—roughly 14 million users, compared to Facebook's 200 million—the site's growth has been phenomenal, with user numbers going up 1,382 percent in 2008, way above Facebook's paltry 228 percent rise. Something about the way the service works—its immediacy, spontaneity, the ability to broadcast your musings into cyberspace while walking down the street—has charmed people into spilling all manner of thoughts and observations—quotidian, profound, and idiotic—through Twitter messages, or "tweets."

As a result, the site has become a petri dish for human behavior, capturing everything from celebrity antics to acts of heroism to inane blunders that result in lawsuits, job losses, and even political coups. Here are the best and worst examples of Twitter behavior in the past few months.

THE WORST TWEETS

5) Despite reports that social networks like Twitter and Facebook can improve productivity on the job, they also provide plenty of opportunities to embarrass your employer, not to mention yourself. And when an imprudent tweet is seen by the wrong eyes, it could mean losing a job before you've even started. Earlier this month, a new hire at Cisco, identified only by his Twitter name "theconnor," tweeted the following upon receiving the good news:

Cisco management, and the rest of the Internet, took no time in discovering the message, and the sorry tweeter—mockingly dubbed "Cisco Fatty"—was soon lampooned in tweets, Web sites, and even videos. His story has become the "dooced" of Twitter—a cautionary tale for tweet-happy employees worldwide.

4) Celebrities have been quick to embrace Twitter, attracting thousands of followers interested in the (often mundane; even boring) thoughts and lives of the stars. Of course, this means plenty of opportunity for actors and singers to let their personalities run rampant without the filter of various handlers. So far, the most notorious celebrity Twitter-foul belongs to Courtney Love, who has been sued by fashion designer Dawn Simorangkir for defamation based on Love's tweets and other Internet rants. After commissioning clothes from Simorangkir’s Boudoir Queen clothing line, Love became enraged when she was sent a bill for the clothes. When Simorangkir suspended her work for Love, the singer launched a full Twitter assault against the designer, accusing her of being a "nasty, lying, hosebag thief" who had committed "assault and burglary." According to the complaint, Love also threatened Simorangkir, saying, "oi vey don't f--k with my wardrobe or you will end up in a circle of corched earth hunted til your dead."

Here's a slightly more cogent example, in which Love accuses her rival of theft:

3) Large corporations have been quick to get into the Twitter act, repurposing it for marketing and public relations. However, the freedom and lack of constraints on the platform can create messy situations for companies and brands trying to tame Twitter for their own gain. Take the Mars Corporation, which owns Skittles. The marketing department thought it was being pretty smart when, as part of a publicity campaign, it redirected its homepage to a Twitter search of any tweets that contain the word "skittles." Unfortunately for the company, Internet-savvy comedian Baratunde Thurston used the opportunity to tweet some less-than-flattering remarks about the product, which then appeared on the homepage. Here's one of the less raunchy examples:

2) Bosses aren't the only ones catching imprudent tweets: Clients can see them, too—and hold them against you. James Andrews, a vice president at a public relations and marketing agency, managed to alienate a good chunk of the employees of one of his largest clients with a single tweet. During a trip to FedEx headquarters in Memphis—where, ironically, he was scheduled to give a presentation on digital media—he tweeted the following:

The tweet was soon picked up by blogs, where it was seen by FedEx employees and management. Andrews was flamed across the blogosphere, and he issued an apology, as did his employer. FedEx, for its part, issued a formal statement accepting the apology.

1) Politics and social media have been quick and easy bedfellows, with the presidential election solidifying the importance of the Internet in campaigning and serving in office. And while Democrats won the social media race (as well as the election) in 2008, members of both parties have flooded the Twitter waves in the past few months. At present, more than 120 members of Congress are using the microblogging service, while major Republican players like Newt Gingrich and Karl Rove are gaining popularity on the site. Unsurprisingly, all this political-insider tweeting can lead to sticky situations, and an errant tweet can have significant blowback, as Virginia pol Jeff Frederick found out this winter. While the Democrats controlled the Virginia State Senate, Democratic senator Ralph Northam agreed to switch sides in February, a move that would have shifted the balance of power toward the Republicans. Frederick, chairman of the state Republican Party, brought it all down with this tweet, posted on February 10:

Given that the Internet is ubiquitous in state senators' offices, the Democrats soon saw his tweet, prompting the majority leader to adjourn the session and the remaining Democratic senators to rally around the defecting senator, effectively forcing him to change his mind.