IMDbiTunes link: IMDb - Free
Looking at the IMDb app it's easy to see where the perception that a lot of apps are "just a website" comes from. Aesthetically it does look pretty much like just the website, but reformatted for the iPad.
However, add features such as embedded trailers, a history of visited pages and, yes, formatting much better suited to the iPad than just the website (pop-overs are particularly well-used) makes the IMDb iPad app much more usable than "just the website."
Plus, it's a free app, and you can hardly complain about streamlined, easy to use and well laid out access to IMDb's formidable archive of film and television related trivia when it isn't costing you a penny.
IMDb is almost as effective a time sink as Wikipedia and the IMDb app is a great way to access it. Slicker than Deepwater and twice as fun.