In the past, I listed a few types on websites can that generate money. This time I am listing some additional ideas:
A site with online games, such as games using Flash technology can bring money even if you allow visitors to play the games for free. What you can do is offer some extra options that use points and sell these points for money. You can also monetize such a site with ads.
Forums that are very popular are known to generate a lot of money from ads. What I think is challenging in case of forums that they heavily depend of the community. It you fail to build a strong community, then you might not see a lot of money.
With Google being so popular it might be difficult to create a successful search engine, but on the other hand, if you have some innovative idea this might work. Take into account that your competition is very strong.
A blog about a certain product. Just write news and information about this particular product and over time you should be receiving decent traffic. Of course, it would be wise to write about a product that will not disappear from the market in a short period of time.
I the future I will try to list some additional money making ideas.