Here is a term that I've seen used a couple times before:
Word/Term: Twincest
Meaning: Romance between a pair of twins, such as Fred and George Weasley.
Original Fandom(s), If Known: No idea, sorry.
These are specific to the Harry Potter fandom, so you might not want them, but I thought they were funny so I'll submit them anyway.
Word/Term: VaporMort, Vapor!Mort
Meaning: Lord Voldemort in his "spirit" form, as he was between his first downfall and when he got his body back in GoF.
Original Fandom(s), If Known: Harry Potter
Word/Term: QuirrelMort, Quirrel!Mort
Meaning: The combined Quirrel/Voldemort entity in PS.
Original Fandom(s), If Known: Harry Potter
Word/Term: UglyBaby!Mort
Meaning: Voldemort as he was seen briefly in GoF, in a temporary baby-like body.
Original Fandom(s), If Known: Harry Potter
Also I have some info on the "Bleeprin" that was mentioned by jaymesilvermane. It was coined by Meir Brin for the PPC, and can be found
here. Also, the term "nuzgul" originated in OFUM and can be found
here.
By the way, there is a dead link in the entry on "fanfic".