How much money do films make?

I wanted to rent a movie today and went to IMDB to check it out, and for the first time for some reason I noticed it mentioned the gross box office income. The film was Gone Baby Gone, and it had an estimated budget of $19mUSD and a box office gros of $20mUSD. That seems like an awful lot of work, investment, and risk for a very very small payoff.

Now I’m interested, hehe, where can I find more detailed information on income/expenses for major feature films?