Intended to help find fanfiction. This particular version, you enter a category link from Archive of Our Own such as:
for Harry Potter.
It then implements a search, taking between 2.5 and 5 minutes (so as to not hit their servers too many times). Finally, it returns results in a specialized sort, ie the ratio of kudos to hits. The point being to find stories that have high rates of kudos, but perhaps not very many views, or, theoretically, undiscovered gems of fanfiction.