Laura's comment yesterday about 100 pages of research equaling 1 page of narrative reminded me of one of my writing pet peeves/things I used to do a lot:
This, I feel, is one of the bigger problems for new writers. You have all this background information that the character needs to fulfill the quest or the reader needs to understand the story and, in the rush to get to the "meat" of the tale, you let the reader know absolutely everything up front. This has the unintended consequence of making the reader disappear faster than pizza at a Weight Watchers convention (brownie points for anyone who knows the comic I stole that from).
Same thing goes for all of the research we do as writers. It's all necessary for verisimilitude, but those reams of research may only serve to make sure one comment by one character makes sense to someone who knows the topic better than you do. For example, I chopped an entire page and a half from a friend's WIP because it was an information dump (she thanked me for it, by the way). All that (necessary to her story) background is better spread throughout the story, rather than up front.
I tried to do the same thing in SON OF MAGIC and CALLARION AT NIGHT. You never get all the info right at the get-go and, in fact, there's (hopefully) enough vague tidbits that you keep reading to find out if your questions get answered/that offhand comment in Chapter Three plays out in Chapter Seventeen and so on.
Information dumps can work, however. J.K. Rowling was asked, at one point, if she'd ever have Ron and Harry read Hogwarts:A History. She replied that they'd never read the book because then she couldn't use Hermione to explain everything to both them and, by extension, the reader. It's a brilliant way to get the background information out without resorting to massive blocks of text that makes the reader's eyes glaze over.
This is rare though, and most writers who attempt to do end up resulting in the dreaded info dump. The lesson to take away from all this is to only let your character and readers enough to drive the story forward. Otherwise, what's the point of writing it?