Dante's Divine Comedy...an interesting skerry--of Earth, Hell, Purgatory, and Heaven--to say the least!
The Greece of Eurpides...Greek city states if the gods (and their semi-human offspring) actively took part in the affairs of humans. (Helpful hints for a long and happy life...if the most powerful sorceress in the world, who also happens to be a granddaughter of Apollo, abandons her country and her family for you, do not ever dump her for some other woman. Oh, and don't tick off Dionysus, either, by the way; he certainly has a sense of humor, but you may not like what he considers just or funny.)
Higurashi no Naku Koro ni...let's do the time warp again. But maybe not with so many knives and bludgeons this time, okay? Check out...
http://en.wikipedia.org/wiki/Higurashi_no_Naku_Koro_ni
...for more details. And then run like hell. If you can.
Jane Austen Meets Frankenstein...what if ALL of the fictional worlds of the late 18th and early 19th century lived together in one timeline? While Darcy falls in love with Elizabeth Bennet, the Ancient Mariner is trapped in the icy waters near the South Pole, the School for Scandal is spreading stories in London, and Frankenstein's monster is murdering people. Oh, and all the real history of 1775 to 1825 is going on, too.
Enjoy.
Mark