This script does one thing only, but it's quite useful. In world view, it shows you which of your cities is closest to the selected island. Thus, with this script installed, it's easy to make sure you're sending your trade fleet from the right city when buying or transporting. It's also handy when you need to send military to a specified target, and need to know your nearest mustering point.
Do you see something cheap on the market? Want to make sure your ships get there as quickly as possible?
1) Just send minimum one ship from your city where you see the materials available on the market.
2) Then click on Military overview to see your fleet movements.
3) There, click on the highlighted name of the destination city where the goods are being sold.
4) Then click on the "World" link in front of the island name (-not- the Show World button!). The Nearest City script shows you which of your cities is nearest to that destination!
If your nearest city was different from the one you just sent a fleet to, then you can select that city, go to the trading post, and send a fleet to buy from there, then go to military view and recall the fleet that's taking longer.
I have two suggestions that would improve the script further:
1) in the list of your cities provided, link the city names to the cities so one can directly select a different city if necessary.
2) give the nearest city info in Island view -- even just the nearest one, linkified, without the whole list, would be very handy.