I take it you mean actual books, not the books in-game? 'Cause that does sounds pretty awesome.
It'd be neat if they published more in-depth books around the wars over-seas in the Third Era, Valenwood armies, and backstories on Dominion plans and heads of organizations and stuff.
Like, bits throughout the book that have mini profiles on important people throughout Tamriel and stuff.
I'm getting hyped about my own ideas.
This would be nice, but it needs to handled properly. The Greg Keyes novels were nice in some aspects, but the plot and characters were pretty weak. If TES does get any more books made, they need to be written by someone who can better use the source materiel.
All this said, if there was some way in the world I could take a shot at it... :P
A series that actually has decently written books would be the Assassin Creed books. I have only read two of them (Black Flag and another I borrowed off a friend that I can't remember the title of but was based off Conor) and they were pretty good. Filled in missing details from the games. I haven't read the two TES books but I would love to see more of them.