If you want to create even more interesting maps, with features that are not available through existing Drupal modules, you need to become familiar with JavaScript and with the JavaScript libraries that are used to create maps.

If you are using the OpenLayers module, get to know the OpenLayers JavaScript library. OpenLayers explained how to add new JavaScript Behaviors to your maps. There are many Behaviors in the OpenLayers JavaScript library that are not implemented in the OpenLayers module, but which you can activate using the method in Chapter 5. For example, it would be possible to add a shape on your map that rotates, with the speed of rotation representing the intensity of a tornado. The OpenLayers examples page contains an example showing the geometry.rotate method. Then again, you could create labels on your map that change depending on the zoom level. Find an example that is close to what you want to do, then view its source code to work out how it achieves its effect. In conjunction with that, study the class documentation. For the rotating tornado, you would read the documentation for the OpenLayers.Geometry.LineString class. There is one book in English on OpenLayers, which is listed in Appendix A.