Well, almost everything. That's what is offered at ProCon.org, a serious and interesting website which aims to promote "critical thinking, education, and informed citizenship by presenting controversial issues in a straightforward, nonpartisan, primarily pro-con format."
The Health & Medicine section might be of greatest interest to my readers. Among other things, it contains a page on children's vaccinations with a huge array of information.
Beyond specific content, this is also a useful site for those thinking more about how we make decisions -- a skill transferable across the whole spectrum of life's questions. So the page "Golf: is it a sport?" might be just as useful. :)