There are three existing initiatives/projects that I think will help if webmasters make use of them.

One is the new voluntary site labeling program ("Restricted To Adults") at RTALabel.org. That will work in any browser that has content filtering capabilities, and they are working on getting future versions of browsers to recognize the tag and refuse to display the content if the filtering options are turned on.

The second is Digimarc's adult content watermark, which does the same thing, the image itself won't display if the browser filter is turned on.

The third thing is an identity system project to actually identify the user sitting at the computer through a third-party system similar to DNS; the idea being you would, in order to join a site with ccbill or epoch (or any other site that wanted to use the identity verification), have to provide information that a third party would use to verify your actual age. The cool thing about it is that the site you're viewing wouldn't have to know who you are at all, and the identity verification service wouldn't know what site you're visiting, so anonymity would be preserved. (Of course, if you're paying with a card, the payment processor would know from your card info, just as it does now.)

So I think that all of the technology that we need to responsibly keep children away from our content is there and, for the most part, already implemented. All we need is for the industry to agree to use it. But of course, the problem is that until most everyone in the industry starts using it, no one will want to, because it will no doubt cut down on conversion and probably on sales as well.