So-called "people search" sites like PeopleFinders, WhitePages and many more all buy, sell and trade your private information for profit. Few people are happy to know how any stranger - or marketing company - can obtain their home address for a few dollars, and that it's challenging to stop.

But not impossible.

As we learned in How To Remove Yourself from People Search Websites, “peoplefinder” sites are giant databases that make money by selling your profile to anyone with a credit card.

See also: How people search sites get your information - and what you can do about it our gallery:

For instance, PeopleFinders is one of the largest of these sites. Right now, they're having a sale.

At PeopleFinders it's only $0.95 for anyone to buy your full name and any variations, address, phone number, the names of your relatives, your age and date of birth and they promise up to 40 years of your address history.

Big spenders can pay $39.95 and get all the above plus information about any property you own, your marriage and/or divorce records, any bankruptcy information, a sex offender check and a criminal record check.

There are dozens of people finder sites, and many of them are owned by each other. They're the front face of a shady world where data dealers comb public records, buy and trade information from online shops and social networks, and scrape sites for anyone and everyone's profile information. Then they mash it all up into a profile - of you - and put it up for sale.

Many people have looked themselves up to find records incorrectly associated with them. This is amusing when you're mistaken for an opera singer, but chilling if a criminal record is involved.

While one of the big sites Intelius conceded in an SEC filing that the information that it and similar companies sell is often inaccurate and out of date, many people can find their own home addresses with a few clicks.

I think a lot of people don't realize that when they click "agree" on social networks and other websites that the little footnote about agreeing to share data with third parties means their phone number gets sold to literally anyone for a dollar. Or that their profile data gets added to these databases, filling in any information gaps on their various people finder profiles.

Right now it seems like data dealers are really taking advantage of the fact that few people understand this.

That's why lately I've really been getting mad when sites like Facebook and Google+ require legal birth names for users. They claim that real name use makes people behave better, when there is no evidence to support this assertion and many people are having the opposite experience. I think the truth is more that a legal name makes the personal data Facebook and Google+ collect more valuable, because it's accurate.

I also bristle when people try to use the fact that these social media sites are free, in any kind of "like it or leave it" argument. They're not free when you consider that the end result of handing over your profile information will be making some company down the line $35 off your "free" participation on social sites. Or that when Facebook sells or trades your phone number and address, they are not giving you a cut of the profits.

I worry that it's created a world where privacy and certain kinds of personal safety are a commodity.

So, you can opt-out of people finder sites, but you can also do what you can to stop the personal-information Wikileaks everyone is unknowingly experiencing at the hands of data buyers and sellers.

Where People Finder Sites Get Their Data On You

I'll start with the bad news first. As we know, these data grifters get some of their info on you by getting their hands on your public records.

There aren't any laws against it, but I'm starting to think there should be. Before the internet, access to public records was something that wasn't easy. Their physical locations and procedure surrounding document access made the barrier to access prohibitive - not like today where any creep can stalk you and check out your public records from his couch.

My interview subject from How To Remove Yourself, attorney and privacy expert at Abine Sarah A. Downey, explains public records:

"Public record" is a legally defined term, and it includes anything prepared by a government employee or in furtherance of government records. All public records are accessible through the Freedom of Information (FOI) Act, both federal and state. Each state's FOI is different, which causes conflicts. For example, Florida has a very liberal FOI that allows the public posting of mugshots, which has led to a fairly lucrative - and controversial - business of mugshot websites.

According to Downey, this is a list of the types of sources that people finder sites use to compile their listings:

Real estate transactions (including appraisals)

Trademark filings

Marriage licenses and divorce decrees

Any unsealed lawsuits or legal actions

Birth certificates

Death certificates

Census statistics

Voter registrations

Drivers licenses

Government spending reports

Political campaign contributions

Sex offender registrations

Legislation minutes

Business and entity filings

Professional and business licenses

Criminal records

Data dealers and people finder sites also get your data from public record sources consisting of information voluntarily provided by individuals, although arguably without knowledge that it'd be used for something beyond the purpose for which you originally provided it. Downey listed these sources as examples:

Sweepstakes

Surveys

Rebate and warranty cards

Online account registrations and profiles

Forum posts

Social networking info, which sometimes depends on the site's TOU regarding sharing info with third parties, as well as your privacy selections on that site (such as your Facebook "likes" and interests, your friends, your tweets, the work information you provide to LinkedIn)

Speaking of social networks... Ad networks are the same kind of personal information data dealers. If you were one of the 70 million MySpace users, your profile now belongs to the targeted advertising network that bought them on June 29, 2011 - Specific Media.

I get the overall sense that there are a few big players here that do everything. By 'everything' I mean:

Both buy, and self-generate, data and lists.

Sell it to individuals (through people finder service storefronts) and companies (other data resellers, AOL, targeted ad companies).

Broker it with partners (post-transaction marketing businesses, analytics firms like KISS Metrics, and the Direct Marketing Association).

After public records and online accounts or registrations, people finder sites collect their information from other people search sites, social networks, online accounts, online tracking software, and more.

In a blog post, people finder site Intelius openly states that another site, Spokeo, compiles data from social networking sites, and they say that Facebook and Twitter are "the face of a hidden world of commercial data brokers."

What You Can Do To Protect Yourself

There isn't much we can do to stop people finder sites from getting public record information about us and making a profit off of it.

Opting out of people finder sites will get your private life off the public market.

After you opt-out, there are a number of things you can do to prevent your info from being re-populated to people search sites:

Only give out your information when you have to. If it's optional, don't do it. Facebook continually prompts me to give them my phone number for "better security" but I'm not falling for it.

Look at your privacy settings on all your social networks; change them or lock them down if you can.

When you do have to give info out for a profile or signup, consider giving the minimum of information, and be strategic about whether or not you give them your actual information. Only give them what's absolutely necessary for site membership.

Be wary of sites that make you register to use them. They're not "free" to use if you give them something of yours they can - and will - sell.

Don't make it easy for sites to make an accurate profile about you, and know that your email address is in the hands of anyone you give it to. Use an alias or a pseudonym, and consider using an anonymous email that forwards to your real inbox to avoid getting spammed.

Think twice before putting content on sites that want you to make a profile, like dating sites.

Know that your likes, check-ins and and +1's are public - not just public, but also profitable for the companies that made the buttons. Think twice about “liking,” “digging,” “upvoting,” and especially “checking in” using Foursquare and other location-based check-in services.

Do what you can to block online tracking; it won't hurt to use browser add-ons that block targeted advertising cookies and trackers.

When you see a people search site being deceptive or feel you've been tricked by them, use this form to report them to the Federal Trade Commission.

I don't want you to think I'm typing this out wearing my finest tinfoil hat - as I explained in How To Remove Yourself, I have been stalked, threatened and harassed by someone that used people finder sites with the stated intent to harm. I was shocked to learn where people finder sites get their information - and horrified that I may have, at some point, voluntarily handed over the information that was used to terrorize me.

But I'm not going to live under a rock and not use the same social sites my friends are all using. Just because I don't want to give up my personal data does not mean I should live a life of exclusion.

I simply think that until we have more privacy rights - especially around the websites we create our profiles on - we need to look out for ourselves and the people we care about.

The people we care about being the spouses and family members that come in your $0.95 file currently for sale at PeopleFinders.

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