Believe it or not, Erik Selvig's chalkboard may prove to be the most important storytelling device used in Thor: The Dark World.
When Selvig is in the insane asylum holding court on the nature of the cosmos, he has a diagram of the World Tree on a chalkboard, covered in doodles and other writing, some of which probably seemed like nonsense--but some of which is pretty important.
First of all, he refers to the overall World Tree as "Universe 616," which as any good Marvel fan knows is the designation of "our" universe in the comic book source material. This is perhaps interesting because many fans had thought that, like the Ultimate Universe comics, the Marvel Cinematic Universe actually took place in its own "universe" that could perhaps one day cross over with 616. That explained the slight differences in character histories, continuity and the like. It seems, though, that unless Selvig is wrong, then the fans were.
Second, we get The Fault referenced. The Fault first appeared in the Dan Abnett/Andy Lanning War of Kings storyline--perhaps not surprising, since we're seeing "their" version of the Guardians of the Galaxy and the Nova Corps in the movie coming up next year. The thing that's really interesting about it isn't that it's Marvel Cosmic or even that it's DnA, though; it's that it could tease The Inhumans, a movie said to be in development at Marvel Studios and one of the major titles Marvel Comics is focusing most of their energy on right now.
The Fault is a tear in the universe that leads to a number of alternate realities. The tear was caused by a Terrigen bomb and was created by Black Bolt, leader of The Inhumans. The story ultimately led to the cosmic crossover The Thanos Imperative, which seems significant considering the involvement of Thanos in both the Avengers and Guardians of the Galaxy corners of the Marvel Cinematic Universe.
The third major thing on the board is The Crossroads.
The Crossroads serves as a nexus point to an infinite number of alien dimensions. Back in The Incredible Hulk #300, Dr. Strange exiled The Hulk to The Crossroads, where his fury could be kind of contained by allowing him access to an infinite number of worlds, none of which had any life on them that could be harmed by his rampages.
That wasn't the last time Strange tried to exile Hulk, of course; at the end of World War Hulk, Strange and the other members of Marvel's Illuminati shot the beast into space, where he would ultimately lead a revolution against a brutal dictator before returning to Earth having sired a child. That story, titled Planet Hulk, has been released as a direct-to-DVD movie. World War Hulk was at one point rumored to be the premise for Avengers 3.0comments
Of course, they also have Kyle + Yost = x, which as far as I can tell is executive producer Craig Kyle and one of the film's writers, Chris Yost, so not everything has a ton of buried meaning, unless it turns out those guys are headed over to Fox to help on the X-Force movie...
Also in a creator-driven rather than universe-driven Easter egg, Thom Williams in the comments below points out, "'JW 2013' in the bottom right corner. Joss Whedon signing his work for an epic Easter Egg compilation?" Seems likely, since Whedon is the Marvel mastermind at Disney right now and one of only a handful of people who would know exactly where each of these story elements might be headed.