Wikipedia is quite a good source for free pictures. And most of them are appropriate for kids as well. And it is in most cases a great resource to verify data, for example the capital of a country.
Also you want to have the search (google and wikipedia) localized. The wikipedia.patch adds a wikipedia search field localized to german. Furthermore it localizes the google search to german and localizes the links at the top left. The file you have to edit is the data/index.html in the Browse activity folder.
Tags: Planetarium, Sugar