Do books serve any purpose?

Do the books that I've been randomly looting off bookshelves serve any purpose other then reading for the lore and then selling? How about random invoices, tattered documents, letters, etc?

Solution 1:

The Bookworm achievement requires you to read 50 books throughout the world.

Additionally, there are certain books scattered throughout the world that give permanent skill bonuses (e.g. Lockpicking, Stealth, Blacksmithing, etc). These books, however, are generally labeled appropriately, such as Skill Book: Lockpicking.

Lastly, there is at least one (if not multiple) collection quest(s) that require you to get books as part of the collection.

Solution 2:

Reading books will contribute towards the Bookworm achievement which requires you to read 50 of them.