Here's an interesting take-over effect I just stumbled across on this Xanga blog. When you roll the mouse over one of the top menu buttons (the one with the green-yellow logo), the page background changes to display a "secret message".
Clicking the button whisks you to the Sublymonal site, where you are asked to enter a code.
When you enter the code (figure this one out on your own), you are introduced to Lymonics.
The whole thing is a promo for Sprite and is somehow tied to Lost. Notice how the fine print on the site says "OBEY" is trademarked by Coca-Cola. Very fitting. Anyway, the whole purpose of the exercise was to point out the nice background-swap effect.