Most binary events that have economic impacts are also either broadly good or bad, which makes the second category difficult. Part of this may be lack of imagination on my part, of course, and as I said previously, I would like to be proved wrong.

Define binary, because my imagination does not come up with many examples that are not more like some linear events, e.g. amount of rain as opposed to "it rains".

Also, in almost all of the cases I come up with, there is a benefactor. With rain people stay indoors and use more electricity, consume more television and hang out more on the internet. With a negative scientific result a product becomes unviable which ensures the market position of another market participant. And so on. Keep in mind that for a prediction market to work in an unbiased manner, there only needs to be a benefactor relative to someone that loses, that is total wealth can decrease, but not uniformly.

Lastly, the rise of the second and third world will ensure that there are more than enough market participants for most questions, at least I think so. I have no model to predict this, but base this on a gut feeling. Maybe we can construct some examples to get a feeling on what point we disagree on?