It's one big MS Word-file, exported to HTML. It would be best if the content is divided into several pages. It definitely needs a different stylesheet, especially for the tables. The maps could be redrawn in SVG and it would be nice to add some interactivity so that layers can be peeled back by the user.
I'd like to help the author clean up this page, if he'll allow it. Would anyone like to join me?
If the author made their data available, it should be reasonably easy to restructure the data a bit then use something like OpenHeatMap (www.openheatmap.com) to create layers on top of Google Maps.
EDIT: Another idea -- if the author made their data available in shapefiles, it'd be easy to use with any mapping program.
We have roughly the same number of accents/dialects as the US, in a tiny fraction of the area. Yes, it does get confusing sometimes.
(Unfortunately the recordings are in WMA. Ewwww. VLC can cope.)