If a site doesn't carry such a statement, and you're doing more than making a purchase there, call and grill a knowledgeable company representative on how safe the site is. Ask if the site uses an outside firm to test its security. Companies generally don't like to provide much detail--because they don't want to give away any secrets--but you need to make sure that they're taking measures to protect their site from intruders.
"At the moment, only a small percentage of people call us to ask about security," says Quote.com's Pedersen. "It's mostly those who understand the technology and are concerned about how we will protect their personal data concerning their net worth. But I think these questions will become increasingly common as people begin to understand the vulnerabilities. I think people should be asking these questions."