What do the oddly positioned letters in "Death Note" title mean? In the original Japanese Death Note title:




the first E is backwards (or, equivalently, rotated through 180 degrees)
the A and Ts are rotated 90 degrees anticlockwise, and
the N is rotated a few degrees clockwise.


Do any of these stylistic choices have a known significance, or were they chosen at random?
They're definitely not random. From an artistic perspective, this typographic choice accomplishes 3 things:


The 90 degree rotation of the Ts and the A form the shape of an arrow or a knife tip. The E in front of this "tip" is reversed to make sure this can be seen easily--the back of the letter forms an uninterrupted surface that the "arrow" is striking. If the E was the right way, it would look a little like a knife fighting with a fork, so kinda silly. Overall, the design has the letters of "Deathnote" form a weapon. This echoes the mechanics of the plot, where the letters you write in a Death Note are literally the weapon that kills someone.
The title has "death" in it, and the show in general has people being killed off. In fact, one of the main points is to see who is smart or lucky enough to survive. The typography cleverly suggests this theme. Some of the letters are already "horizontal" because of reason #1 above. Tilting the N slightly makes it look like the letters are keeling over one by one, connecting the typography to the theme of people dying off. 
Why is N specifically chosen to be tilted? a) because it's in the middle of a 3 letter block, so for compositional reasons b) it also might be the artist being cute by hinting at the character N and trying to foreshadow his role by drawing attention to that letter.


So basically, one answer is that typography is being used as an artistic device in many ways to suggest themes in the show. There may be other, non-artistic reasons that I'm not aware of, so additional answers are possible. That's the beauty of visual art, it can do many things at once on many levels.