Be prepared:
To help minimize and resolve identity theft if your wallet or purse is lost or stolen:
As of April 15, 2003, you can have a two-year fraud alert placed on your account with each organization by calling just one of them. They will also put you on a two-year opt-out list for credit and insurance pre-screening. You will also receive a credit report from each of them. Be sure to look at each report carefully, as the three organizations share very little information with each other.
Before April 15, 2003, you had to call each credit organization separately, the fraud alert policies varied (e.g., 90 days for Experian, 12 months for Trans-Union), and Experian didn't automatically put you on the opt-out list. Of course, you can always sign up for the opt-out list at any time, but it's nice that they do it automatically, now, as part of your report of identity theft.
If you believe identity theft has already occurred:
The Motley Fool has an excellent article that tells the story of one of the victims of the big identity theft racket that was busted in the summer of 2002. The article includes some good tips on protecting your identity.
Thanks to the Fair and Accurate Credit Transactions Act that was enacted in December 2003, consumers can receive a free copy annually of their credit report from each of the three major credit bureaus. Starting December 1, 2004, citizens of Western states could go to single website and from there easily reach the locations on the Experian, TransUnion, and Equifax websites where you can request one free credit report annually. This service was rolled out to the rest of the US over the next year.
American Express used to offer a service called Private Payments that would allow you to charge purchases to your American Express account without revealing your actual account number. Unfortunately, they appear to have eliminated this service. From some information on their website about their privacy statement: "The Private Payments section has been removed in conjunction with the April 15, 2004 service decommission."
With certain Visa cards (it depends on the issuing institution), a program from Visa called Verified by Visa allows you to add a level of password protection to some of your online purchases. If you shop online with a supporting vendor, you will be prompted for the additional password you set up for your Visa card when you complete your purchase.