it's a latin verse from something (i used to know it, but now i forget) but it's used as common text filler for formatting and set-up of webspaces
and the necronomicin origionated in the books by H.P. Lovecraft and as such are total works of fiction, never truly existed, and you'd be surprised at how many mini-cults there are around different works of fiction, the biggest being the bible (partially ripped off the story of gilgamesh, with that there flood thing).
sorry i ramble and am a fan of lovecraft