The ideal speech topic is interesting, engaging and above all, something that the speaker cares about. If the speaker doesn't particularly care about what he or she is arguing, it will be very obvious. Topics for persuasive speeches can range from politics to social issues to music or art. Keep in mind that a good speech could acknowledge the other point of view or consider that issues are not black and white.
Topics in Technology and Science
Discuss whether social media, such as Facebook, twitter, Myspace and dating sites, are good things or bad things. Do the same with cell phones, genetic modification or any other new technology. Argue whether NASA should be well funded, whether violent video games should be allowed, whether green energy research or military research is more important, or whether small children should be allowed to use computers.
Topics in Politics
There are a huge number of potential topics in the field of politics. You can assess the career of some political figure: argue whether Bush was an effective president, or whether Malcom X's tactics were justified. Alternately, focus on one of the many hot-button issues in politics today, such as abortion, gay rights, climate change and other environmental issues, socialised health care, evolution, terrorism, corporate lobbying, animal rights, campaign finance reform, war, globalisation or whether or not TV pundits like Glenn Beck improve the political dialogue.
Many of these topics are somewhat political in nature, but if done properly, their language will tend more towards informative scientific explanations and away from polemical or hyperbolic language. Topics include global warming, acid rain, deforestation, soil degradation, over population, overfishing, poaching, whaling, endangered species or bad farming practices. You can also choose a much more specific topic, such as whether a copper mine should be built in a specific area, whether snowmobiles should be allowed in Yellowstone or whether hydroelectric dams are good because they reduce fossil fuel use or bad because they disrupt habitats.
Topics in Education
Most students will have an opinion on how a school should be run. Topics include whether cafeterias should serve healthier food, whether students should be allowed to have mp3 players or phones at school, whether the day should be started earlier or later or whether students should be allowed to leave school grounds for lunch.