David E. Schultz and S. T. Joshi are editing many volumes of H. P. Lovecraft's Letters, over twenty volumes, that will be publish'd by Hippocampus Press. Some few sets will be produced in hardcover, but I think most will be in trade pb editions, as has been the case for Letters to Rheinhart Kleiner (Hippocampus Press, 2005) and Letters to Alfred Galpin (2003). Letters to James F. Morton will be available late this year or sometime in 2011. The next two-volume hardcover set, to be publish'd next year, will be the correspondence between H. P. Lovecraft and Clark Ashton Smith, and it shou'd be spectacular. The hardcover sets of correspondence between HPL and Derleth (Essential Solitude, 2008) and HPL and Robert E. Howard (A Means to Freedom, 2009) are out of print and fetching ridiculous prices at Amazon; however, arrangements have been made for a trade pb reprinting of A Means to Freedom. One really wonderful volume is Mysteries of Time and Spirit--The Letters of H. P. Lovecraft and Donald Wandrei (Night Shade Books, 2002) and O Fortunate Floridian: H. P. Lovecraft's Letters to R. H. Barlow (University of Tampa Press, 2007).
One fascinating and entertaining volume is Lord of a Visible World--An Autobiography in Letters, in which editors Joshi and Schultz allow Lovecraft to "tell" the story of his life in carefully edited letters accompanied with notes. From ye inside flap: "In Lord of a Visible World, the editors have amassed and arranged the letters of this prolific writer into the story of his life. The volume traces Lovecraft's upbringing in Providence, Rhode Island, his involvement with the pulp magazine, Weird Tales, his short-lived marriage, and his later status as the preeminent man of letters in his field." This volume is a wonderful place to begin one's adventure in ye reading of Grandpa's epistles. And, Great Yuggoth!, that cover! They did some eerie things to ye photo of HPL, his eyes do not look natural, & in this photo he looks every eldritch inch a master haunted by supernatural horror in Literature. If I wasn't so computer clueless I would post an image of ye cover here. But I do not understand such things. For example, I meant only to underline the word "wonderful" above, but everything following it is now underlined and I don't know how to undo that. Oy!