They're Nurykabe tilesets. I may or may not be on a secret project, but I'm not, so don't worry. Yep, no secret project.
Anyway, how do I use those tilesets? >.< Planetes, #41, is surprisingly self-explanatory for a Nurykabe tileset, but I don't know how to use any of the others. :|
On another thread, Nurykabe himself posted examples of all of his tilesets up to #34, but none of them after that. Halp? :c
Edit: Aha, nevermind. Turns out Nurykabe has examples on his own website! Usin' those, you can delete this now. :P