There are many ways to make money off a website. The higher quality your site is, the more monetization options you will have. Also, the type of niche you are in will also determine your options.
A lot of people make the mistake of going for the money, only undertaking sites in niches that seem highly monetizable like finance, investment or health related topics. They do this regardless of the amount of knowledge they have with the topic. When you start a site on a topic for which you are not knowledgeable, it becomes difficult to compete and therefore, hard to get traffic. They get buried in search results and no matter what monetization methods they use, they can't make a profit.
It's far better to choose a niche for which you have a lot of knowledge and passion. Your content will be better, and this will help you to compete.
When looking at monetizing that topic, creativity can go a long way to move you past the usual Adsense method. Ebooks can be written and sold, affiliate products recommended for a commission and things like Clickbank products sold.
When you know your niche and can truly help people, you step outside of the usual and can go beyond that. You can sell consulting or an offline service. Sell DVDs or CDs about a topic and just about anything you can think of.
If you're just writing a site to make money, but don't know anything about the subject, your monetization opportunities greatly diminished.
The moral of the story? Create a great site, make your visitors happy and then use your imagination. It can take you very far.