If such evidence is found, they help you close potentially compromised accounts, place fraud alerts at the big credit bureaus and in general minimize damage.

Often the free services are meant to entice you to sign up for a more robust pay version costing $15 or so a month.

• IDSafe is a freebie from TrustedID that monitors black-market sites for data concerning up to three credit cards and your Social Security number. It also gives you a free annual credit report and score (not a FICO, the most commonly used score, but a reasonable estimate).

• AllClear ID has a free service by Debix that provides Internet surveillance and notification of suspicious activity, and help with repairing your identity if information is stolen.

• Some banks and credit unions offer free ID theft protection services. These range from help in placing fraud alerts on compromised accounts to obtaining copies of your credit reports.

• AOL and Internet providers such as Comcast provide customers — at no charge — some of the protections of IDSafe and AllClear ID.

But whether free or for-fee, these services aren't foolproof. They can't, for instance, protect against your information getting into the wrong hands through "data breach" attacks on corporate computers.

So it's up to you to keep up your own vigilance. That means regularly checking your credit reports for suspicious activity. You can get them for free at AnnualCreditReport.com. Each of the three credit-reporting bureaus is required by the Fair Credit Reporting Act to give you a free copy of your report once a year, so it's best to look at a different one every four months.

As a proactive measure, you may consider placing a fraud alert or security freeze on your files at the credit bureaus. There may be a fee involved.

At all times you should carefully guard your financial account numbers, your Social Security number and date of birth.

And don't click on links that you find on sketchy websites or incoming emails. They could infect your computer with software that steals your identity.

Also of interest: Virus protection scam to access your computer. >>

Sid Kirchheimer is the author of Scam-Proof Your Life, published by AARP Books/Sterling.