Once upon a time we wanted to build a social movie database. At first there was only the name: Cineasts, the movie enthusiasts who have a burning passion for movies. So we went ahead and bought the domain cineasts.net, and so we were off to a good start.
We had some ideas about the domain model too. There would obviously be actors playing roles in movies. We also needed someone to rate the movies - enter the cineast. And cineasts, being the social people they are, they wanted to make friends with other fellow cineasts. Imagine instantly finding someone to watch a movie with, or share movie preferences with. Even better, finding new friends and movies based on what you and your friends like.
When we looked for possible sources of data, IMDB was our first stop. But they're a bit expensive for our taste, charging $15k USD for data access. Fortunately, we found themoviedb.org which provides user-generated data for free. They also have liberal terms and conditions, and a nice API for retrieving the data.
We had many more ideas, but we wanted to get something out there quickly. Here is how we envisioned the final website: