In a sign that we Bookmen truly are trendsetters, we discussed The Price of Salt, the Patricia Highsmith novel, back in 2005. That was a full decade before "Carol," the film based on the book and directed by Todd Haynes, opened in theaters. I haven't seen it yet, but hope to do so this week.
Prior to that, we discussed an even more famous Highsmith novel, The Talented Mr. Ripley, way back in 2000. However, that was the year after the acclaimed film based on it, of the same title, was released, so we can't claim any prescience there.
When I did a quick rundown of our reading list (a permanent part of this blog) just now, I found something like 15-20 titles which have also been adapted into screenplays for cinema or TV (not counting those that began life as works intended for the stage, like "The Normal Heart" or "A Streetcar Named Desire." And there may well be more.