Mining the events of years past yields infinite non-fiction topics. Biographical portraits of historical figures such as French scientist Marie Curie, American inventor Thomas Edison, Greek philosopher Aristotle or Victorian novelist Charles Dickens make good non-fiction topics. Try recounting a famous historical event, such as Lincoln's Emancipation Proclamation or the sinking of the Titanic. While requiring some research, relating a historical event that has been all but forgotten can make for great non-fiction. Start at the library or on the Internet and find a fascinating world event that is no longer celebrated or popularly known.
The political domain lends itself to various non-fiction topics. Write about the powers of the president or the vice-president. You can also recount how a bill becomes a law, or the differences between the American Congressional system of government and the British parliamentary system. On a different note, analyzing a contemporary world political event, such as a war taking place overseas or the state of another country's economy, makes an excellent non-fiction political topic.
Sometimes writing about what you love is easiest when it comes to non-fiction. If you are a sports fanatic, plenty of good non-fiction topics await you. A topic as general as the history of professional football can attract a broad audience. For something more specialized, analyze which team will win this year's World Series, or match up a contemporary athlete in any sport against historical greats.
Science non-fiction topics can be for interest's sake or with a specific goal in mind. Write a profile of a planet, the solar system or an animal for the more general crowd. Showing how something works, such as a volcano or a hurricane, can also be an interesting topic. You can also choose a topic that sets out to make an argument, such as why global warming must be combated, or why the dinosaurs became extinct.