Check out the source code of the Wunderground API.
svn checkout http://wunderground-core.googlecode.com/svn/trunk/ wunderground-core-read-only
In the package de.mbenning.weather.wunderground.api.domain there is a class called WeatherStations. There you will find the content of all weather stations you can call in your code. Right now there are only a few ones:
public static final Map<String, WeatherStation> ALL = new HashMap<String, WeatherStation>();
static {
ALL.put("INRWKLEV2", INRWKLEV2_KLEVE);
ALL.put("INORDRHE110", INORDRHE110_GOCH);
ALL.put("IDRENTHE48", IDRENTHE48_COEVORDEN);
ALL.put("IZEELAND13", IZEELAND13_GOES);
ALL.put("INORDRHE72", INORDRHE72_DORTMUND);
ALL.put("INOORDBR35", INOORDBR35_BOXMEER);
};
All others won't work.