Geography Games:

You could do these games in a text format, but a world map would be better. Wikipedia and Wikimedia Commons have such maps. Trouble finding one? Just ask for help in the forum, and I (or others) will be glad to give you more specific assistance. In the meantime, see:
http://commons.wikimedia.org/wiki/Atlas_of_the_world

World’s Greatest Rivers (Streamflow):
http://en.wikipedia.org/wiki/List_of_rivers_by_average_discharge

World’s Longest Rivers:
http://en.wikipedia.org/wiki/Longest_rivers
Again, a world map is the best route to go here.

Most Populous Islands:
http://en.wikipedia.org/wiki/List_of_islands_by_population
Largest Islands by area has already been done. But this hasn’t. Simple world map would help.

History Games:

Naval Battles of WWII:
There are several WWII games, and some show naval battles. But there is no comprehensive, global game for naval battles. Taranto, River Plate, Denmark Strait, sinking of Bismark, Coral Sea, Midway, Leyte Gulf, and on and on. There were battles in the Arctic and Indian Oceans, as well. Any halfway decent world map would suffice. A little help with info:

http://en.wikipedia.org/wiki/List_of_military_engagements_of_World_War_II#Naval_engagements

Great Battles of WWI:
Nope, there are no WWI games. You could use the site’s own map of Europe here. To be avoided: a pile of dots for all the battles on the western front. To do it right: show several in the west, several on the eastern front, Gallipoli, and some of the naval actions (Jutland, sinking of Lusitania, etc.) You could glean this all from the many WWI articles on Wikipedia.

The Greatest Naval Battles in History.
You need a world map and this link:
http://en.wikipedia.org/wiki/Largest_naval_battle_in_history
It has the five largest and another dozen big ones listed.

People Games:

Astronauts and Cosmonauts.
You could get a list from Wikipedia and either do pics (if available) or list accomplishments in text. For example, for the clue Yuri Gagarin, click on the dot by “First in Space”, for Neil Armstrong, “First on the Moon”. And who did the first space walk for US and USSR, who were the first women for each, etc.

Celebrity Mugshots (Male).
I’m surprised no one has done this. A web search turns up whole sites dedicated to this. This, of course if a picture game. And probably, could lead to parts 2, 3,…

Celebrity Mugshots (Female).
Yeah, pretty much the same.