I've noticed that ads for postdoctoral positions emphasize the skill set that one must have for a particular position. That said, what are the areas of research to avoid because they give you few transferable skills and hence limit your range of possible postdoctoral positions?
For example, String Theory might be an area to avoid because it gives you virtually no experience with using scientific software packages that might essential for post docs in other areas. Any others?
(My motivation for asking this question is that I think it might be nice to roam into other interdisciplinary areas and fields post-PhD, rather than restrict oneself to a certain field for life.)