In addition to text files typed out of these hymnals, there are now articles with lyrics and poetic meters for all the songs in the Nauvoo Hymnal and the 1845 LDS hymnal. Here are the links to their articles, respectively:
The Nauvoo Hymnal The 1845 LDS Hymnal
I plan to do the 1835 LDS hymnal (the first one) soon.
This is one of the more valuable old text only hymnals (and one of the least-known).
Although this hymnal contains a very large amount of hymns from other similar hymnals, one might be surprised at some of the selections, seeing as they're not all generally thought of as hymns used by the LDS church in the distant past. These include the following (among others):
When I Survey the Wondrous Cross
Hail the Blest Morn (i.e. Brightest and Best)
Come Thou Fount of Every Blessing (with all three verses instead of just the usual two included in later LDS hymnals).
and search for HymnWiki. The one that says Go will take you directly to an article if you type in its name. The one that says search brings up search results every time. The one that says Forums is for the HymnWiki Nabble forums.
Though it's had it for a while, probably, I recommend adding the Cyberhymnal's plugin from there, too (or anything else helpful).
Now that that's over with, I still need to type up the Nauvoo Hymnal (I've done a small portion of it).
I found someone else with a site dedicated to preserving LDS hymns (though that's not all HymnWiki is dedicated to preserving). It's called the Lost Hymns Project. There's some interesting stuff there.
As a side note, I noticed that the Nauvoo Hymnal has Amazing Grace in it. Some people kept telling me that Amazing Grace was in an old LDS hymnal, but I never believed them; it's true (no. 118), but they didn't have the seventh verse people sometimes use today. I wonder if there was a future edition with it and music (maybe the Psalmody? I could check that out).
I'm currently working on the Nauvoo Hynmal (typing it out into a txt file). I don't know how long it will take, as I might not have lots of time, all the time. Anyway, that's the one scheduled for me to finish next. After that, I'll likely do the 1839 and 1843 LDS hymnals in the same fashion.
After that, maybe I'll get back to sheet music (either that, or I'll type the lyrics from the public domain hymnals with sheet music, first - or so I plan now).
This hymnal is particularly exciting, seeing as it contains a larger number of hymns than any previous LDS hymnals (as far as I've come to find).
I've finished typing out A Collection of Sacred Hymns for the Church of Jesus Christ of Latter Day Saints, 1845 in a txt file. This is the one where there was no downloadable scanned image of the entire book (you could download the separate file for each page, but that'll take some time; now, you can even get a searchable text file for it).
Anyway, I'm excited: I should have finished this eons ago, but for some reason I began focusing on other things and didn't put the last few hours needed to finish it for quite a while (it didn't take long to type, overall). This book has several songs not in the Manchester Hymnal.
Here's a link to the HymnWiki article for the hymnal. You can download it from there:
Well, my old roommate moved, and so my connection to his grandpa has been delayed until August - so, I didn't get a look at his copy of the Manchester Hymnal (I don't know what edition it was) to fix the mistakes in the version I had typed. However, I found a misplaced link to another online version of the Manchester Hymnal (the fourth edition, from 1844), and I made corrections based on that, with the exception of one punctuation mark that I found from some hymn that was online elsewhere (apparently, the 1844 online version of the Manchester Hymnal is kind of messed up with the pages and such; I think the 1840 one, even in print, was done better, mostly).
Today, I also found a bunch of other LDS hymnals, with scanned images, at BYU's Online Collections - I had not known these existed, but they are from 1839, 1841, 1843, and 1845 (I listed them on HymnWiki). The Nauvoo Hymnal is of particular interest (apparently, it's a second edition, or so, of the first LDS hymnal, with more songs).
The hymns themselves still need articles, though. Also, we need to figure out who composed the tunes and who wrote the lyrics, as well as what the tune names are (for most of the songs).
This should be a valuable resource to many, if they check it out. All the hymns (except for a chord or two in the last song) are two part songs (one treble clef part and one bass clef part). They seem to me to be rather unique, among hymns.
Anyway, I know of no other place where you can download the sheet music for most of these songs, yet. They're public domain, though, so people can put them on their sites freely.