I had heard about glass stoppers (yet another alternative to natural cork), but I have yet to encounter one in real life, so I found this Alcoa Closure Systems International glass stopper page to be interesting. It's also a great example of how pictures can really enhance someone's understanding (what it's like to open a bottle using one of these closures, as well as a "cutaway view").
Ever thought of doing a "How We Make Our Wine" story-in-text-and-pictures for your site? Sort of a virtual tour of your winery? If, so, you might also be interested in Inertia's series on how to build a (virtual) tasting room on your Web site.