Bank of America cardholders can create a virtual card number by logging in to the online banking site, clicking the View Options link to the right of the credit card account, and then choosing Create a ShopSafe account number. From there, you can set a spending limit and expiration date. Head to for more on ShopSafe.

If you have a Discover card, you create a virtual number via . Discover also offers downloadable software for Windows that runs from the system tray. (Click the Download Now button under Desktop Version on the same Web page.) The software can pop up to allow you to create a virtual card number when you're making an online purchase, and it can fill in forms.

For Citibank, log in to online banking and click on Virtual Account Numbers in the upper-right corner. You can also download software by logging in to or , selecting Get a Virtual Account Number from the 'Tools and Services' drop-down menu, and then clicking Download Now. Citi's software works much the same as Discover's desktop app does.

PayPal users can grab a browser plug-in for Internet Explorer or Firefox (only for Windows) by logging in to their account, choosing Products & Services, and then clicking the PayPal Plug-in link under 'More Products and Services'. The plug-in adds an icon to the upper-right corner of the Web browser with drop-down menu options to create a Secure Card virtual number and perform other PayPal tasks.