Websites Generating Revenue

There are a lot of websites out there that generate some sort of revenue. This time I would like to focus of websites that offer some kind of tools or useful, information that people may need. Basically, there are two main ways that a webmaster can generate money by having such a website. The first way is to charge useful per month for access to the website, while the other way is to get revenue from ads. Both ways have pluses and minuses, but I think that allowing visitors to access the website for free is important, because in my opinion this is what the Internet is all about. That is why in most cases getting revenue from ads might be the right thing to do.