Important events work well for informative speech topics as a specific event can be chosen to interest a specific audience. You could discuss events that are surrounded with a certain element of controversy, such as the JFK assassination, the O.J. Simpson trial, Marilyn Monroe's death and Watergate. Choosing a controversial event might be a good choice due to the fact that you can combine information on the subject with mystery and intrigue, which helps keep an audience interested.
Picking a topic about a specific process is also great for an informative speech as it has a very specific focus, which often works well for a speech that must be delivered within a certain time range. Some processes that would make effective informative speech topics are: starting a business, cooking a certain recipe, how to play certain games such as chess, how to sew or knit, how to get a book published, how to write resumes and how to make a website. With a process speech, you can also tailor it to a specific audience's interests if you know them beforehand.
Delivering an informative speech on a concept opens up a variety of topics such as beliefs, ideas and theories. Some unique topics that fit this category would be Scientology, UFOs, folklore or urban legends, evolution, creationism, Communism, voodoo, origins of superstitions and cults.
Informative speeches on an object include subject matters such as animals, people, places and products. Some unique topics might include: the FBI or CIA, obesity, celebrities, dangerous snakes and spiders, electric cars, video games, Egypt and Iran.