Currently, we have a bunch of tolkien tags:
(as mentioned by @JasonBaker:)
(These^ are for the movies, I think.)
Do we need all of those tags?
But to we need the individual work tags? Questions may be from one book, but answers will often be from the entire canon.
As for middle-earth... We need to either clarify usage or burninate it. As it is, it's being used on some tolkien questions, because middle-earth is almost a synonym of tolkien. Notice that I said almost. The difference is, that middle-earth can be used to refer to the place, not just the works that are set there (as I think that the usage should be).