Add 2 new fields to article: City and country
both should be part of the article description.
City: just a normal text box
Country should be a customizable dropdownlist (I would display DE, AT, CH, BE) because these are the countries where most people of my communities come from.
Customizable: I can choose which countries will be displayed, and the order, or at least the default country.
I also want to implement a modification of your zip-code hack, therefore the country is neccessary.