How can I apply a Computer Science degree towards a career in a research-related position of another field? I'm not interested in becoming an academic.  Rather, I'm interested in opportunities for a Computer Science (or related) major to work in research, either in industry, but also particularly in academia, and particularly in fields where CS skills/knowledge could be applied to social sciences (or cognitive science). This includes anywhere from simply being a programmer that happens to work in a research setting to doing actual dirty work with computational modeling that may even require some domain knowledge of the topic at hand.

My problem is that I don't really know what sorts of opportunities exist out there and how to get to those opportunities.  I'm not opposed to getting a graduate (master's) degree in a specific field, getting research experience, and developing broad expertise around a subject area.  In fact, that could be great.

However, I get the impression that in academia, you center your research around highly specific areas and that becomes your life.  To be honest, there is not one highly specific area of interest that I have (at least not yet) where I would be passionate enough to dedicate and invest such a huge portion of my life towards studying and researching, not to mention I don't want to tie myself down to any specific subject nor the poor job market of academia (sucks, I know).

I'm more interested in breadth and the ability to work on interesting projects.  Part of the reason I went into Computer Science was because of how applicable it was to many fields.  While I find Computer Science and programming to be incredibly engaging, my heart truly lies in the study of people, and it would be a dream to merge the two worlds together.  In some sense, you could say I would love to work in academia without becoming a full-out-academic, by leveraging my background into another field.  But I would like to make it a viable career path.

A random list of subjects/areas/words to capture my interests: cognitive science, computational models of narratives/belief/reasoning, agent-based modeling, complex systems, social network analysis, human computer interaction.

I know a field like bioinformatics or computational biology is pretty huge, and I've often read about ways to enter those fields (e.g. be a CS person who enters from the outside and picks up the biology knowledge as they go along, or someone who has done biology research their whole career and is now learning and picking up CS/programming skills to assist their research).  I'm interested in opportunities to be more of the former, for the reasons I have outlined above.  Though I would say, the more I can wet my feet into the domain area, the more preferable.

What paths can I take?  What are some emerging fields?  What jobs exist and in what numbers?  How can I get there?
I merely skimmed through your post, but from the title already I find the answer to be straightforward and very interesting. As a CS student and having done plenty of research, I feel that CS is a great field but other fields are equally interesting. CS will allow you to inject yourself into more or less anything you like. The simplest example is simulation, even though physicists and other specialists are usually hired to automate all the formulas and programmers merely implement, you could easily have those specialists show you everything you apply and have them explain it to you. Then you just go on to simulate something else and pick up knowledge from another field. 
Even more obscure and theoretical things can use CS, a simple example is artificial speech, combine it with AI and you could get into interesting concepts. However simulation also could apply, with some more difficulty, to sociology.
I find that game programming is a field that allows one to get into anything he likes, loop up the term serious games, they are games that are made for training professionals and are often used by the army or corporations. Try some out and see what skills are needed from non computer related specialists to get an idea.
As for getting masters degrees and such, you can go for many different ones that combine sciences, creating a chain between them. You do not necessarily need to specialize, if you invest serious time and effort you could prove to the world that you specialize in just applying CS to anything. 
About Job opportunities, often it is helpful to create your own, you can find people interested in a specific area that are willing to help you out and start up your own project, this will help in more than one ways, first is that you might actually get something good out of it and eventually make a living from the project, second is you get hands-on experience which goes straight to the CV and proving you are serious about this, and third is that this may well attract academics and professionals to call you in for collaboration. 
I personally have more or less the same problem, I am mostly into CS, am aiming for game development, but I am immensely fascinated by economics, forensics, chemistry, engines, history, even shipbuilding, so I have started making my own games. It has payed off very fast, I get to become a microsoft student partner in October while I have had a proposition from a professional to collaborate - even though on a small project. 
Finally, you can fill in your spare time with online courses, I picked up forensic science on Coursera, from the university of Singapore, it takes little time, I've learned many things from different fields and it shows you're more into learning tons of stuff than just getting something satisfying and then lying around. A master of course is worth a thousand of these as the rest of the community here told me, but it's fast, fun, effective, and it's worth something.
Hope I helped, sorry for the length of the text, felt that it was necessary to cover your questions and show as much as possible of the immense flexibility imaginative people have with CS. Cheers.