The only narrative text I know of that's unpublished is the original English of
The Complaint of Mim the Dwarf. It would be about four pages long.
In non-narrative form, there's probably a bunch of linguistic stuff; I believe both
Parma Eldalamberon and
Vinyar Tengwar have their next issue at least theoretically in the works, and I know I've seen mention of them having a bunch of stuff to work through. They are mostly going to be short essays and wordlists though, and pretty limited in their distribution/accessibility.
There's at least one substantial linguistic piece out there in the wings: the "fairly complete Taliska grammar" mentioned in HoME V, which has been with the people behind the linguistic stuff for ages uncounted. Another
substantial piece of Tolkien writing I'd like to see would be the complete version of
Letter 210, his response to the Zimmerman script. (I'd also like to see the script treatment itself!) And based on
Galin's post in this thread, there
might be an unabridged "History of Galadriel and Celeborn" somewhere. But I don't know of any significant narratives that have been hinted at but never seen.
~
I also wondered about the opposite question: what Tolkien tales are
already published, either by themselves or buried somewhere in HoME? Excluding the many discarded drafts, and allowing the published Silmarillion to stand in for the latest JRR Tolkien version (I know, I know), my chronological(ish) list of the Tales of Arda runs like this:
- The Book of Lost Tales (HoME I & II; near-complete and very different original Silmarillion)
- The Awakening of the Quendi (HoME XI; fairy-tale of the origin of the Elves)
- Silmarillion
- Athrabeth Finrod ah Andreth (HoME X; Finrod's conversation with Beren's great-aunt)
- Beren & Luthien
- Lay of Leithian (HoME III; epic poem)
- The Complain of Mim the Dwarf (published only in German)
- Children of Hurin
- Lay of the Children of Hurin (HoME III; epic poem)
- The Wanderings of Hurin (HoME XI; coda to the Children of Hurin)
- Fall of Gondolin
- Unfinished Tales
- Tal-Elmar (HoME XII; beginning of a Second Age tale)
- Fall of Numenor
- Hobbit
- The Adventures of Tom Bombadil
- LotR
- LotR Epilogue (HoME IX; Sam and his children, years after Frodo's departure)
- The New Shadow (HoME XII; beginning of a sequel to LotR)
- The Lost Road (HoME V; unfinished time-travel novel of Numenor)
- The Notion Club Papers (HoME IX; unfinished literary commentary turned time-travel novel of Numenor)
Other than the Book of Lost Tales (which I would love to see a "reader's edition" of), and the names used in some of the stories (notably The Lost Road and the early Lay of Leithian, you can pretty much read these as a single consistent narrative. The relatively minor differences can be put down to different accounts of the same tale - clearly, whoever was writing them down didn't actually know whether Hurin took a pack of bandits and a hoarde of gold to Doriath, or went by himself with a single necklace.
(There are also a fair number of non-Middle-earth tales, but I've gone on too long already. ^_^)
hS