Hebrew manuscripts abound with substitutes for the Tetragrammaton. Jacob Lauterbach wrote an article with a long list of examples. Having a critical list, one that catalogues usage of different letters and graphic schemes by date and geographic distribution, would be a boon to scholars. But, as David Golinkin has pointed out, this work has yet to be done, and Lauterbach's list is not particularly useful.
My question is this - when did spelling out השם, Hashem, first crop up? I don't remember seeing it discussed anywhere, but chances are it is. I would have assumed it was quite late, but the manuscript I am working on now is probably from around 1300.
Googling the word Hashem, I found a preponderance of messianic sites. I don't know why. Any ideas on that?
There are two auditory memories that Hashem brings to me. The first is Rav Mordechai Breuer talking about the documents in the story of the Ten Plagues. One of the two is, of course, that of Shem Havayah.
The other memory is from a Beit Morashah conference on mysticism. Prof. Philip Alexander spoke about Metatron, calling him "Hashem Ha-Katan". With his accent, it sounded really funny, and has stuck in my mind ever since.
Jacob Lauterbach, “Substitutes for the Tetragrammaton”, Proceedings of the American Academy for Jewish Research 1/2 (1930-1931), pp. 39-67
David Golinkin, Ginzei Rosh Hashanah: Manuscript Fragments of Bavli Rosh Hashanah from the Cairo Genizah, New York and Jerusalem 2000, p. 7