I liked using gnuplot in this way so much, I decided to hone in on Europe, of course the densest information in the data source. Constraining the range of the longitude to 6 degrees West to 23 degrees East, you get the chart below.
Gnuplot chart of locations in Europe since 2003
#!/usr/local/bin/gnuplot -persist
set terminal png size 1600, 700
set output "EuropeLocation.png"
set grid
set title "Everywhere We've Been in Europe since 2003"
set datafile separator "|"
#set xrange [-150:170] # full range
set xrange [-6:28] # Europe only
set xlabel "longitude"
set ylabel "latitude"
set style line 1 lc rgb "red"
plot './location.dat' using 3:4:1 notitle with labels,'./location.dat' using 3:4 notitle with lines ls 1;