The new official site will be up in about a month but for now here is a brief description of what the site may look like:
The Marauder's Map, which on the site is detailed and patterned as if it came out of a Tolkien anthology, serves, naturally, as the navigational tool for the entire site. It folds out like an accordion, pops up like a pop-up book, leading around a very detailed map of Hogwarts (and the different elements of the site). This may not be exactly how the map looks in the movie, as different elements are needed for a web site, but it's based on it.
Check out TLC for the rest of the report.