As usual with many new games, there are hundreds of Let's Plays and guides to go along with it.
Here's a featured guide on how to kill the high level boss "Skeletron." This video was featured on the main page of Terrariaonline.com not too long ago.
There's also a comic series!
View the rest of the series in this thread on the official forums.
The game sold over 200,000 copies the first week! At 10$ per copy of the game, thats over $2 Million in the first week!
Blue (One of the founders of the game) gave a "Behind the Scenes" view of the developer's To-Do list of things coming in the following months. Including dedicated servers, PvP games, weather (Seasons), environmental sounds, and other cool little additions to the game!
Again, if you're interested in buying the game, its only 10$ on steam! Go check it out!