How to determine the monetization sources of a startup web service

I am "Russian" by nature, and maybe due to that I am finding it hard to see what may seem obvious to a western person. I read a lot of investment stories on techcrunch.com about "what it seems absolutely free forever" sites are getting investments in large quantities.

Surely founders of these projects need to provide a monetization forecast for investors to be ready to give money.

Take recent gojee investment story. A web site that provides recipe information got a $2.8m financing. What they were to show as a potential monetization source when they were presenting the project to investors? If you have the answer, please try to describe how did you come up with it. Thanks.

P.S. The only source I can think of is advertising restaurants on recipe pages. May it be it for such project?

Monetization can take many forms. As Facebook and Google have shown, free services that "allow" you to share your activities, habits, thoughts and ideas are marketing gold. Every year, billions (if not more) are spent on marketing products from groceries to golf balls. Imagine a recipe site that allowed you to create shopping lists, or even better, you could just "one-click" (yes, intentional Amazon reference) and purchase the needed groceries from your local supermarket. It shows your eating habits, and what foods you're likely to buy and not buy.

The old adage that "nothing in this world is free" holds more true in a digital age than it ever has, simply because any small bits of information can be used to help customize marketing, or sold to the highest bidder.

I could go on, but I think that covers your question. Let me know if it doesn't, or if this isn't clear.