World Maps and Atlases
While studying Longitude and Latitude, you would naturally need to refer to maps/atlases of the world. Here are some online maps and atlases that you may find useful.
A very easy-to-use online map service that allows you to view it as a traditional map, as a satellite view, and for some countries, at the street level with photos of the place.
MapQuest World Atlas
You can check the maps of various parts of the world with this online facility.
University of Texas Historical Maps
If you need a historical map, which shows the world at some point in history, this is a good site to try. Note that the collection is far from complete, but there are nonetheless quite a number of maps of different parts of the world at various periods of history.
Perry-Castañeda Library Map Collection
Maps of various parts of the world, some of which were produced by the US Central Intelligence Agency (CIA). The few maps that I checked out appear to be rather good.
Earth From Space
A different kind of map from NASA. It contains a clickable satellite picture of the world, where you can click any location to get a more detailed satellite picture of the area. Beware - the detailed pictures are extremely large. For example, the high resolution version of the map I checked out was 75 megabytes in size! Along with the pictures, you can also click their "Technical Info" link for more information about the country you have located.
CIA World Factbook
The CIA has a publicly accessible compendium of information about the various countries in the world. There is a map of each country as well as concise information about that country's geography, people, government, economy, communications, transportation, and military.