Facebook is the world’s largest social networking site, with more than 800 million active users – many of whom enjoy posting status updates, photos of themselves, and comments about their own lives or other people’s activities.

Twitter, the micro-blogging site, is equally popular – if not in numbers, then certainly in terms of how engaged people become once they start dashing off 140-character tweets and developing a following.

Despite all the benefits Facebook and Twitter may offer – social interaction, creative expression, and real-time sharing of news and information – there are also many ways in which Facebook and Twitter could lead to some serious economic damage if you’re not careful.

Here are six ways Facebook, Twitter and other social media sites can hurt you financially:

1.    You could lose a job or promotion 

According to a Reppler study, 91% of employers use social networks to screen job applicants. In fact, 69% of employers say they’ve rejected a job candidate based on something they saw about the person on a social networking site.

Clearly, saying or doing the wrong thing on Facebook or Twitter could cost you a job or take you out of the running for a much-desired promotion.

That’s why we’ve all heard stories about social media exploits coming back to burn people. (Think: those college frat pictures showing you binge-drinking, that careless tweet about how much you “hate” your job or boss, or that topless photo you posted during Mardi Gras).

So be smart about your social networking posts. Remember that Facebook and Twitter have definite career consequences for you, and thus serious financial ramifications as well.

2.    You could become a victim of theft 

I’m always amazed at people who announce practically every detail of their lives, including their present whereabouts, on social media sites such as Facebook and Twitter.

Before you use social media to broadcast to the world that you are currently or will soon be on vacation in Mexico for a week, realize that crooks actively troll social networking pages looking for easy targets to victimize.

By telling the world that you’re currently out of the country or traveling out of town on business – or even that you just bought a great new home entertainment system – you could be setting yourself up to get robbed at your house or apartment.

And if thieves break into your home while you’re away, they could also get access to personal data, like your bank accounts or Social Security number – putting you at risk of identity theft too.

This is such a problem that Allstate, the big insurance company, recommends that people use smart social media strategies to deter burglary and theft. One suggestion Allstate makes: think twice before you check in on Foursquare, use Twitter to share a “wish-you-were-here!” message to your followers, or post real-time Facebook pictures of yourself sipping margaritas in the Caribbean.

3.    Bill collectors can track you down 

Under federal law, bill collectors are restricted in terms of how and when they can contact you about debts you supposedly owe. That’s one of the protections afforded to consumers under the Fair Debt Collection Practices Act (FDCPA). The FDCPA also prohibits debt collectors from telling others about your alleged bills.

But right now, the law is unclear on whether or not a bill collector can attempt to contact you through certain forms of social media. After all, most consumer protection laws, including the FDCPA, were written in a pre-Facebook era.

Besides, even if the FDCPA directly addressed this topic, bill collectors routinely flout the law. Little wonder, then, that unscrupulous debt collectors have been known to “friend” people on Facebook – and then later ask for or demand cash.

Some collection agents use an online “friendship” to get to know you, including where you work. Then they try to weasel their way into your wallet. Other debt collectors take a more aggressive approach, employing online threats, coercion, and other strong-arm tactics on Facebook to try to publicly embarrass debtors.

Using intimidation and harassment is illegal – no matter how a debt collector contacts you. But that doesn’t stop it from happening all the time.

5 Ways to Avoid Debt Collectors on Facebook and Twitter 

Whether their technique is nasty or nice, it’s becoming more common for debt collectors and creditors to use social media platforms as a way to spy on you and your lifestyle, gauge your financial standing, and ultimately try to get cash from you.

4.    Almost anyone can tarnish your professional reputation 

One of the financial hazards of using sites like Facebook and Twitter is that anyone can publicly bash you – at any time and for any reason – and do serious harm to your personal or professional reputation. Their gripes may be legitimate or completely fabricated and baseless.

Either way, once someone hell-bent on publicly trashing you takes their beef to Facebook, Twitter or other social networking venues, the damage (at some level) is done. This goes for individuals and businesses alike.

Sure, your friends may know that some jilted ex-boyfriend is simply making up nasty rumors about you and spreading false lies all over the Internet to humiliate you. But what about that prospective employer you’re trying to impress or that new business account or client you’re trying to land?

Likewise for businesses, including small business owners, having someone bad-mouth you on Facebook or Twitter has huge negative financial consequences.

According to the American Express Global Customer Service Barometer, when people using social media for customer service have a negative customer service experience, more than 80% of them halt a purchase with that business. Additionally, those same individuals will tell an average of 53 other people about their bad experience, the American Express survey revealed.

So a company suffers not just the loss of that one customer’s business – but also potentially dozens or maybe hundreds of other people too. If a person’s complaints go really viral through social networks, many thousands or even millions of prospective customers could form a negative impression about the company, inflicting serious financial harm.

5.    An ex spouse can use your Facebook activity against you in divorce 

If you ever split up with your spouse, and there are any financial or personal issues being contested, expect your ex – and his or her attorney – to comb through your Facebook posts and other social media activities searching for ammunition.

They’ll be looking for evidence of your assets, spending, lifestyle, affairs you may have had and more, according to lawyers who say the use of social media in divorce proceedings is on the rise. And all of it could wind up costing you dearly in divorce court.

Even if you manage to settle out of court, and avoid appearing before a judge, if a bitter former spouse gleans certain information about you from Facebook – stuff you’d long forgotten about – he or she will likely be able to extract a bigger financial settlement from you.

Oh, and if you think you’re safe just by deleting information or changing your passwords, think again. Several judges have ruled that divorcing parties can be ordered to turn over passwords, usernames, logins and deleted data from their social networking sites.

6.    You could be legally served court papers 

Speaking of court, a divorce battle isn’t the only thing to worry about when it comes to Facebook or Twitter hurting you financially.

Recently, the rapper Flo Rida was served with a damages claim via Facebook. An Australian music festival promoter is suing Flo Rida (whose real name is Tramar Dillard) for an alleged breach of contract over a concert gig gone sour.

The promoter claims to have paid Flo Rida $56,800 to perform at a concert in Sydney, but the artist failed to show up, according to Sydney’s Daily Telegraph.

The newspaper further reports that the promoter, called Mothership Music, made various unsuccessful efforts to serve Flo Rida personally, including attending other concerts in Australia where he performed. But process servers could never get past huge crowds, including the rapper’s bodyguards and entourage.

So when traditional efforts to serve the rapper failed, the New South Wales District Court froze Flo Rida’s assets in Australia, an ultimately allowed a claim to be served on him via Facebook rather than in person.

Obviously, this case involves extenuating circumstances – not the least of which is that the two parties live on opposite sides of the globe.

But this isn’t the first time that courts have allowed the use of social media to serve legal documents. It’s previously happened in Australia and Canada with Facebook. And a U.K. judge also allowed someone to be served via Twitter in 2009.

Legal experts say they expect the trend to continue. That’s not far-fetched when you consider that millions of Americans (not just entertainers) travel for business or pleasure each year.

Any of them could have a personal or business dispute that winds up leading to litigation. If they can’t be tracked down locally through traditional means, it’s not difficult to see that foreign courts would allow people to be served via social media.

While that does not yet appear to have happened in the U.S., I can envision scenarios under which judges might permit someone to be legally served via Facebook or Twitter.

One possible scenario: a father who has skipped town and moved out of state might be served via Facebook in a child custody or child support case, or another type of personal or business lawsuit. Again, it doesn’t happen now, as people have to usually get served in-person and with a hard copy, or sometimes via email.

But who knows about the future, as social media and other forms of electronic communication grow?

As for celebrities and high-profile entertainers like Flo Rida, who aren’t exactly hiding their whereabouts, the irony is that Facebook is a double-edged sword.

Though he was served court papers via Facebook, Flo Rida has also benefited greatly from the giant social media site, using it to help build his massive fan base.

As it turns out, Flo Rida is an active Facebook user. Right now, the rapper’s fan page has more than 6 million likes on Facebook.