Basically the studios each expect a film to make X amount of dollars at the box office, and when it makes far less then it is a flop. It is very rare when you get a studio destroying disaster like Heaven's Gate ( 1980 ) because most movies will eventually make what they lost on the initial release back on television and home video.
One interesting anomaly is Young Einstein ( 1988 ) which lost Warner Bros. a lot of money because they spent millions in promotion and made only $11 million at the box office. However, in Australia, it's country of origin, the movie broke box office records. So Young Einstein is only a flop in the United States, and a blockbuster elsewhere.
Something else needs to be taken into consideration. The box office of each film is from the date it was released until today. So basically, a film like Rocky Horror Picture Show which bombed on it's initial release, continued to make money as a midnight movie, and is still making money in theaters to this day. But that means when you look for the box office of a movie on Wikipedia or IMDb, that you will get the combined total from the initial domestic release, all the foreign releases, and all the reissue releases. For example, the listed box office on Star Wars ( 1977 ) is not just the money it made in the 70s, but all the re releases including the Special Edition release. Also, it is not just the budget you need to take into account but how much was spent on distribution and promotion. So trying to find out if a movie made or lost money on it's initial release will involve a little more research. Usually Wikipedia also has a paragraph on how much the film made or lost on it's initial release, but not always.
Otherwise, this would be a very easy list to complete. Just start with a list of your 200 favorite films, then look to see what they made at the box office and cut all the ones that were hits. I know for a fact that my all time favorite movie bombed at the box office, so I already know what my #1 is.