Other Tolkien writings

[Annunfuiniel]

I knew that Tolkien had written and published poetry in some scale but I had no idea how vast was the list of his works until I came across this list. I was stunned! I haven't read any of those works named on the list (few of those named I have seen mentioned in other connections too) but some seem to have straight connections to the LoTR and other major works of Tolkien (for example "Bilbo's Last Song (At the Grey Havens)").
So, has anyone studied these Tolkien writings? Especially those letters mentioned; they aren't published in H.Carpenter's "The Letters of J.R.R. Tolkien" not at least all of them. How vast is the amount of this sort of material, hidden in the archives? Is there a need for a new compilation??