Remember when I wrote that entry about Crocs? Slate.com linked to it and credited me with coining the term "Croc Conundrum". Soon thereafter, I was getting calls from CBC Radio and was gaining recognition as a Crocs expert. That's still the case.
A journalism student at The University of Delaware is writing an article on the "Croc Shoe Epidemic" and she contacted me to see if I'd be willing to grant her an interview. Apparently a link from Slate.com is all that's required to make you an expert in any given field. If Slate.com had linked to my entry about my torn ACL in 2003, I'd likely being getting interview requests from medical students and invitations to speak at medical conferences.
Anyone can be an expert in anything. All you need is hyperlink or two.