Coloring a map according to mapped database values

Question

Question: On http://www.bbc.co.uk/news/10150007

one can see a map of european countries colored according to state debt/deficit. Now I would have already found it useful several times if I was able to do such a thing myself, for example to visualize regional sales data.

Does anybody know: Is there any (OpenSource) tool with which I can color a world/continental/reginal map according to colors mapped to values in a database ?

Or any tool that can construct a custom map ?

Or if there is no such thing, how would one do such a thing oneselfs ?
Get the outlines of countries from somewhere,
make everything outside the country outlines transparent,
set the coordinates and z-indeces to stack several images over one another,
and then replace the base color with the selected color in each image,
then merge the result to a single picture ?

Answer 1

I normally do this in R. Here are a bunch of examples of how to do this in R.

I also played a bit with QQis, and IIRC it can take input from a postgres PostGIS file.

The canonical commercial tool is ArcView, but it ends up being pricey.

The standard file format for maps is ESRI Shapefiles. These are actually collections of files with the attributes stored in a DBase IV format. Googling for 'shapefile viewer' will get you lots of tools.

There is also mapserver, which allows you to generate maps directly to the web.