(FORTUNE Small Business) – Stolen credit cards, computer crashes, lawsuits--oh my!--any of these things leave an e-commerce site vulnerable to unexpected financial hardship. Protecting your slice of cyberspace from ruin is no different from covering yourself when the neighbor's tree goes through your roof: Buy insurance.

E-commerce insurance is taking hold in the industry. J.S. Wurzler Underwriting Managers, based in Lansing, Mich., and Minnesota's St. Paul Companies both offer policies aimed at protecting e-commerce sites from a variety of liabilities. If your e-commerce site crashes because of an error by a computer technician, a virus, or a hacker attack, the insurance can compensate you for lost revenues and pay for the costs of computer repair, virus removal, and other necessary tasks. Wurzler's premiums start at about $6,000 a year for a few hundred thousand dollars of coverage and go up to $250,000 a year for millions of dollars of coverage.

Tom Shipley, founder of T.Shipley.com, based in Maitland, Fla., got insurance because unlike brick-and-mortar stores, Internet-only sellers like him have nothing to fall back on if their sites break down. "If you're offline for two, three, four, six hours--that's lost income," says Shipley.

Getting a policy involves the same hassles as getting health insurance--your site has to get a physical, er, security checkup first. And that might be worth more than all the insurance you can buy.

--Robert S. Anthony