Making maps with ggvis with some examples showing:

• basic map creation
• basic maps with points/labels
• dynamic choropleths (with various scales)
• applying projections and custom color fills
• apply projections and projecting coordinates for plotting

The R file lets you play interactively with each example. The Rmd file shows what the plots look like in static format. The Shiny code (ui.R, server.R) provides an interactive version in a Shiny app context.

The Rmd has also been published on RPubs and there's a blog post with slightly more expository than the code.

One of the caveats with ggvis is that you need an online context for interactively (making things like interactive choropleths useless without such a context). You'd need to account for this in the Rmd by setting up a faux-facet series for the maps, either with a <table> or <div> grid.

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• Maine GeoJSON from http://catalog.opendata.city/hu/dataset/maine-counties-polygon/resource/ee88d12c-a832-4e4f-a93c-dfd693694688
• Maine crime data from http://muskie.usm.maine.edu/justiceresearch/datacenter.html
• Maine population data from http://www.maine.gov/economist/census/
• US GeoJSON from http://eric.clst.org/Stuff/USGeoJSON
• Drought data from http://droughtmonitor.unl.edu/MapsAndData/GISData.aspx
• World GeoJSON from http://www.naturalearthdata.com/downloads/
• Launch sites kml from http://en.wikipedia.org/wiki/List_of_rocket_launch_sites