I'm drawing (choropleth) maps visualizing language use in big text corpora, e.g. words which are attributed to places. Currently I'm doing that using R and the cshapes Package (http://nils.weidmann.ws/projects/cshapes/r-package). I'm also experimenting with Nolan's and Lang's R package to produce interactive SVG graphs (http://www.omegahat.org/SVGAnnotation/SVGAnnotationPaper/SVGAnnotationPaper.html) to show tooltips on the map. As you can see here (http://www.bubenhofer.com/sprechtakel/2013/08/06/geocollocations-die-welt-der-zeit/) it works generally, but the resulting SVG (and also PDF) files are huge. There is also the problem of the SVG files produced in R, that all text is converted to vector graphics which again increases the complexity of the plot. This seems to be a known problem of SVG in R (http://stackoverflow.com/questions/17555331/how-to-preserve-text-when-saving-ggplot2-as-svg).
What are better means to produce interactive maps showing a lot of data?