If I was to write a paper on the causes and affects of World War I www.pbs.org/thegreatwar would be a great website to help piece together information. The interactive timeline gives an overview from pre 1914 to up to the end of the war in 1918. The part I find most helpful if I was to be typing a paper on the causes is the section on the year 1914. This timeline gives all the declarations of war issued by each country and also talks about the assassination of Archduke Franz Ferdinand. Also there is a link to search the life of the Archduke, which I find to be quite interesting. Many maps can also be found here to help with the visual aspect. For example it shows the German empire in 1914 as formed by wars in 1871. Bismarck's always thought that a country must be in a majority of three if five great European powers were ever in a dispute.
The next map discusses this, which I found to be interesting. The section I found to be most interesting is the interviews given. Examples include the French perception of the war, and also diversions on the battlefield. I would find these things most useful. This website gives great information on the causes and effects of World War I. From the maps to the interviews to the interactive timeline it has everything you need to become acquainted with the Great War.