Making a living on the web as I do, I find it inconvenient to have to look thru pdfs for data that is ripe for interactive visualization. So I took Pearce's Land Snails of Limestone Communites and Update of Land Snail Distributions in Pennsylvania and added in my own records to create an interactive map of the counties.
Don't know if it works in Internet Explorer, but it works in Chrome and Firefox. Seriously, it's 2011. There is no reason to use Internet Explorer. Let me get on my soapbox and say that Microsoft doesn't give a damn about user experience, web standards, or modern web practices. Use Chrome-- it's the best browser out there. Firefox is fine, too.
Here's the link: