Reason No. 4: Your ISP knows too much

If you think Google knows more about you than your parents do, imagine the kind of dope your ISP could drop if pushed to give up the goods.

As the gateway to all our personal Internet communications, service providers could create detailed logs of everything you've ever done online: e-mail, Web surfing, IM, file downloads, and more. The potential for using such records in criminal investigations (or worse) is huge, which is why some lawmakers have been pushing legislation that requires ISPs to retain user data for a year or longer.

"We are more trusting of ISPs than we should be," says Jim Harper, director of information policy studies at the Cato Institute. "You may not be able to see it, but there's a big stream of data going out of your house through your ISP. It's foolish to rely on ISPs to protect us from their own interests or the government's interests in us."

And it's that second party's interests that send the deepest shivers down most folks' spines.

"I've even heard stories that some ISPs are reselling anonymous data about their traffic," Harper adds. "Won't that suck if we find out the anonymized data they've been selling can be de-anonymized and re-identified."

Can you trust your ISP? Don't be so sure.

Paranoia Meter: 3.5

Reason No. 3: The Feds are on your tail

If the National Security Agency is spying on you, you're probably connected in some way to a terrorist investigation -- even if it's just because you invited your neighbor Ahmed over for a barbecue.

But the FBI can investigate you for all kinds of reasons, and you may never know it until they slap on the cuffs. Are you a vegan, a member of People for the Ethical Treatment of Animals, or part of an antiwar organization? All of these groups have been investigated for "domestic terrorism" since September 11, according to documents obtained by the American Civil Liberties Union under the US Freedom of Information Act.

Under the US Patriot Act, FBI agents can issue NSLs (national security letters) to your employer, bank, ISP, doctor, library, or any other entity demanding your records without a warrant. Recipients of NSLs must comply with the FBI's demands and cannot notify the person under investigation. Between 2003 and 2005, the US Feds issued more than 140,000 such letters, according to a March 2007 report by the inspector general for the Department of Justice.

In a random sample of nearly 300 NSLs, the inspector general found possible violations of FBI procedures or the law in 48 of them, or about one out of every six.

Worse, you can be an absolute saint and still be the target of an NSL. According to a November 2005 report in The Washington Post, "Senior FBI officials acknowledged in interviews that the proliferation of national security letters results primarily from the bureau's new authority to collect intimate facts about people who are not suspected of any wrongdoing."

Feeling paranoid yet?

Paranoia Meter: 4