I agree with Durelin above - those covers are fascinating and beautiful, if unrelated to the tale that lies within. They were my first introduction to "Tolkien's World", which explains why I was so unprepared.
I've always enjoyed looking at the way the black riders on the cover of TTT seem to form out of a swamp...hey, those three covers are almost transitive.
And omgbbq - is that a ...
treefrog on the tree on the cover of "Fellowship"?