Submit portable freeware that you find here. It helps if you include information like description, extraction instruction, Unicode support, whether it writes to the registry, and so on.
Marble is a Virtual Globe and World Atlas that you can use to learn more about Earth. You can pan and zoom around and you can look up places and roads. A mouse click on a place label will provide the respective Wikipedia article.
Another "desert island" app: I just kept sifting through the various different views, maps, and overlays. The detail isn't particularly high, but the overall view is very cool by itself. Additionally, the available plugin system made my mind whirl for a second here. The possibilities of plugging in other tools to this already pretty fantastic mapping program are intriguing.
Oddly I couldn't get the sun shading view to appear on all the different map views.