This program generates a 4096x4096 PNG heatmap of the globe based on
t@h tile sizes, see
http://lists.openstreetmap.org/pipermail/tilesathome/2009-May/005858.html

To generate the map, do:

    wget http://tah.openstreetmap.org/media/filesizes.bz2
    bzip2 -d filesizes.bz2
    perl parse-filesize.pl filesizes > tile-sizes.dat
    perl generate-heatmap.pl tile-sizes.dat > osm-heatmap.png

extra stuff:

    # Only tile sizes
    awk '{print $2}' tile-sizes.dat |sort -n > sizes.dat

    # Unique tile sizes
    awk '{print $2}' tile-sizes.dat |sort -n > sizes-unique.dat

See what RGB values are used for the heatmap:

    perl heatmap-rgb-value.pl sizes-unique.dat $(tail -n1 sizes-unique.dat)