From yesterday's New York Times article on nude vacationing:

SpaFinder.com, an online spa search engine, recently created a separate category for “nudist spa vacations” after noticing an increase in searches for the term. Since November, searches on SpaFinder.com for such trips have averaged about 720 a month—beating out “pet-friendly spas” (284) and “waxing services” (298).

Thanks to Alexandra Fox for the tip!