A high fraction. "A dollar's worth of research" is not a well-defined quantity - that is, the worth of the research produced by a dollar varies a lot depending on whom the dollar is given to. I like to think FHI is good at converting dollars into research. The kind of research I'd prefer to do with unrestricted funds at the moment probably coincides pretty well with what a person with SIAI-typical estimates would prefer, though what can be researched also depends on the capabilities and interests of the research staff one can recruit. (There are various tradeoffs here - e.g. a weaker researcher who has a long record of working in this area or taking a chance with a slighly stronger researcher and risk that she will do irrelevant work? headhunting somebody who is already actively contributing to the area or attempt to involve a new mind who would otherwise not have contributed? etc.)
There are also indirect effects, which might lead to the fraction being larger than one - for example, if discussions, conferences, and various kinds of influence encourage external researchers to enter the field. FHI does some of that, as does the SIAI.
Much of the dispersion is caused by the lack of unrestricted funds (and lack of future funding guarantees). Since we don't have enough funding from private philanthropists, we have to chase academic funding pots, and that then forces us to do some work that is less relevant to the important problems we would rather be working on. It would be unfortunate if potential private funders then looked at the fact that we've done some less-relevant work as a reason not to give.
The site is meant to be improved over time, so any comments that could help do that - nitpicky or not - are very welcome. I especially agree that all unnecessary crankiness should be eliminated.
Reg. .com or .org - If there is a clear sense that the .org would be more appropriate, I could look into obtaining that domain name and moving the site there. This should ideally be done soon, while the site is still young. So far, it seems nobody thinks .com is better all things considered, and some people think .org would be a slightly better; but I'd like a little more data before taking the plunge.
Reg. typos in FAQ - Will be corrected over time as they are discovered.
Reg. design - It could be better, but I'm not a web designer. If somebody here would make a nicer version, I'd gratefully replace the current design.
Reg. comments on draft paper 'The Concept of Existential Risk' - this is the main new original content. It is currently under review for a journal, and I might make some revisions when preparing the final version.
I've moved the site to http://www.existential-risk.org/, changed the visuals, and made some other improvements in response to the suggestions that were made here.
There is also a revised version of the new paper (now titled "Existential RIsk Prevention as the Most Important Task for Humanity"): http://www.existential-risk.org/concept.pdf.