The NSA isn't the only one watching what you do online, and a former Googler is here to help protect you from their prying eyes.

As the World Privacy Forum just told Congress, the bottom feeders of the data brokerage world are making big money selling lists of everything from rape victims and AIDS patients to alcoholics, giving marketers the power to hit those folks with emails, phone calls, and ads – and much of this data is coming from the net. In a report of its own, Senator John Rockefeller and his senate investigation committee highlight the massive amounts of consumer data that brokers collect online and off, starkly criticizing how little we know about how this data is collected and used.

While governments seek legislative rememdies, you might want to take matters into your own hands. Countless tools can help prevent companies from tracking your behavior online. A good place to start is Disconnect2, an open source web browser plugin built by ex-Googler Brian Kennish. The irony is Kennish once worked for DoubleClick, the Google-owned online ad giant that's so intent on targeting ads based on what you do online.

Many companies collect data about you through social networking buttons and widgets, such as Facebook's ubiquitous "Like" button. These widgets send information about your habits to a company like Facebook, which sells the data to others. Similarly, web outfits use browser cookies – little pieces of software that track site visits – to play much the same game. Disconnect2 blocks over 2,500 cookies and tracking scripts, making users practically invisible to advertisers and third-party traffic monitoring tools such as Google Analytics. What it doesn't do is block first-party services. So, if you're on Amazon.com, you'll still see what Amazon recommends based on your behavior.

"The analogy is that in the offline world, if you go to a bookstore and visit the travel section and the clerk asks you what you're looking for and helps you find a book on Italy, that's helpful," Kennish says. "But if the clerk from the bookstore followed you into a restaurant and said 'Hey, I know you're interested in Italy, so maybe I can recommend some pasta dishes for you,' that would be creepy."

Disconnect started life as a tool called Facebook Disconnect, a plugin that blocked the tracking script built into the Facebook buttons and widgets found on websites. Kennish started building the thing after reading a story about a Facebook data breach. "It got me thinking about the social widgets and 'like' buttons and how common they were," he remembers. "Harkening back to my days at Doubleclick, I knew those buttons were transmitting data back home to Facebook. And because social networks were encouraging people to be signed in all the time, a company like Facebook was getting a list, by name, of what sites people were browsing."

He wrote the first version of Facebook Disconnect that night, slapping together a plug-in for Google's Chrome browser. "I just quickly put together this browser extension, put it in the Chrome gallery, and went to sleep not thinking about it," he says. "I thought it would get 50 to 100 users. But it got picked up by TechCrunch, and in a week got like 50,000 users."

The tool's success got him thinking about blocking tracking scripts from other companies, including his own employer: Google. He realized he couldn't keep working for the web giant by day and write code that undermined its business model by night, so he soon quit his job. He thought he'd find another day job, but after presenting at a conference called Launch, he was approached by several venture capitalists. He and a friend, Casey Oppenheim, created a company around Disconnect.

Disconnect is a Benefit Corporation, a breed of company that puts social or environmental concerns ahead of maximizing shareholder value. That means it can keep the code for its plugins free and open source without looking for other, egregious ways of making money. While Evidon, the parent company of a competitor called Ghostery, makes money selling anonymized information about what tracking codes its users are blocking – how's that for irony! – Disconnect merely asks that you pay what you want for its plugin.

"The pay-what-you-want model has turned the extensions into a self-sustaining business," Kennish says. "We make enough from the contributions to have a two to three person team just working on extensions."

But the company is larger than that, and it's looking at other ways to make money from the project. It released an iOS app earlier this year called Disconnect for Kids. "Since Apple doesn't support a pay-what-you-want system on iOS, it's just a paid app," Kennish says. "As we expand into other platforms, we'll experiment with other models. "

But they won't track your behavior. And they won't sell it somewhere else. That you can count on.

Correction: An earlier version of this article stated that Evidon sells information about what ads are being blocked by its software. The article has been updated to reflect the fact that the company sells information about tracking codes, not ads, and that the data it collects is anonymized.