If you're at all familiar with Microformats, or even just a vCard, then you may well be interested in the bookmarklet I've written. If not - get reading - interesting stuff (I'm also planning to convert my film reviews to hReviews).
It allows the user to load an overlaid window on the current page and download and import vCards or iCal items individually.
More detail on my business web site: Left Logic > micrformat bookmarklet.
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By the way, if you don't know what a bookmarklet is here it is in a nutshell: