your chart looks great!
i’ve been halfway thinking about different ways to accomplish a completely automated map today, and i’ll probably take a stab at coding something in the morning (with the UTFgrid approach). i’m guessing loarie probably had the advantage of being able to query directly from the database to get observations. it’s not really practical to get individual observations via the API for some of the top observers because of API limits, but non-staff like us still can get bunches of observations using a CSV download (or a series of downloads). so if you’re going to try to make the map yourself, you’d want to start with the top X observers for your place, then limit your search to the place and those top observers (&user_id=reiner,questagame,etc), then export user_id+obs_id+lat+lng to CSV, then use that as your data source to find the center of mass for each of the top users. (or if you want to try to parse through UTFgrids, let me know, and i can explain the approach in more detail.)