If you're a screenwriter and you're looking to sell a script or put together a pitch, here's two valuable resources: donedealpro.com and boxofficemojo.com. By using the information on those sites, you can get a great idea of what is selling and who's selling it. You can compare various types of buddy movies or check out what kinds of bridal romantic comedies have been selling. In short, you can place your ideas within the context of the whole industry.
For screenwriters who want to improve their craft and make themselves more marketable, that's a never-ending process. And it starts with analysis of what's out there in the marketplace already. So check out donedealpro.com and boxofficemojo.com. And by the way, I get nothing for endorsing them. Nor do get anything by telling you that if you are an aspiring screenwriter, you need to take advantage of the information for writers on wga.org and wgaeast.org. Except satisfaction.