Are there professional cognitive science test subjects?
There are a few people who have been very extensively experimented on because they have unusual brain lesions (which is kind of like the opposite of a skill). The most famous is Henry Molaison (HM), who developed a rare case of episodic anterograde amnesia following surgery for severe epilepsy. He spent the entire latter part of his life in a care institute and was a continuous subject of various learning experiments and imaging studies. Another patient with very specific memory-related lesions is KC, who has been the subject of at least 20 case studies. 

A couple of other studies that might be of interest are West et al. (2008), who recruited experienced video game players in order to find people with strong skills at rapid visual scanning, and research by Eleanor Maguire and colleagues that examined structural changes in the brains of new London taxi drivers as they acquired their fantastically detailed spatial map of the city's streets. 


  West, G. L., Stevens, S. A., Pun, C., &amp; Pratt, J. (2008). Visuospatial
  experience modulates attentional capture: Evidence from action video
  game players. Journal of Vision, 8(16).
  
  Maguire, E. A., Gadian, D. G., Johnsrude, I. S., Good, C. D.,
  Ashburner, J., Frackowiak, R. S., &amp; Frith, C. D. (2000).
  Navigation-related structural change in the hippocampi of taxi
  drivers. Proceedings of the National Academy of Sciences, 97(8),
  4398-4403.