Discworld and LOTR would be fun to write if you really wanted to mess up the worlds. Vetinari gets the Ring and manages to actually do something good with it, Granny Weatherwax could beat up Gollum, Vimes arrests the hobbits for being drunk, the Auditors have to deal with the Ringwraiths...or, on the other hand, elves from Discworld take over Rivendell. Heh.
--kleenexwoman (Personally, I don't see much room for Discworld/LotR unless it's something like this.)
I totally want there to be a battle in the library in book six and all of a sudden, with NO explanation, an orang-otan knuckles through...
--the_patrician, funnily enough. (This referring to book six of Harry Potter.)