Overcomingbias and Lesswrong have seen considerable discussion of several key aspects of the world that do not directly bear on rationality (listed as question-headings, below). These discussions are interesting in two lights.

First, they are interesting because they explore important aspects of our world -- they give data and analysis you might want to know as you figure out how to achieve your goals.
Second, they are interesting as case studies in how groups of aspiring rationalists can go about figuring out what to believe. For example, they can tell us whether careful thinkers do, in practice, end up agreeing on a common set of probability estimates, or whether even aspiring rationalists mostly just stick to their initial hypotheses. We can examine these discussions to gather evidence about whether we can or can't think more productively than communities that don't spend time honing their "rationality".

Does marginal health care spending improve health?

Robin Hanson has argued strongly that it does not, and that a vast chunk of America's national economy is being wasted. Many commenters have disagreed, agreed, or cited research in support of more nuanced positions. You can read the details in Robin Hanson's posts, and the ensuing comments threads:

[Need to list and summarize Hanson's essays and OB posts, here. Also, has anyone else written a post on this stuff worth linking to?]

Should you go to an elite college?

If your goal is income, and if you can get in, then, yes, you should. Hanson reviews the data here.

Cryonics

Eliezer Yudkowsky and Robin Hanson argue that cryonics is a good deal; it offers a non-negligible chance at a much longer life, at a price where, if the chance came labeled "experimental cure for cancer" rather than "experimental cure for apparent death", many would take it.

Relevant blog posts on cryonics.