Single-Level Prestige Classes

Is there much precedent for having prestige classes with ridiculous requirements and only a single level that exist solely to confer some amazing ability? It seems like a natural outgrowth of the modularity of Feats while allowing more flexibility in the abilities granted and the prerequisites required (although I suppose there is nothing but precedence that keeps feats from having all the same prereqs as prestige classes). -Slitherrr 10:51, 2 November 2010 (EDT)