Do you have some time on your hands? Time and patience, that is. Wading through any Wiki can be a crap shoot, but I've found some interesting stuff in TV TROPES. Want to know what books, TV shows, films, and Anime feature a character with an obnoxious laugh (the laugh meant to convey the character's overall badness)? Want to know what films use the plot trope of the "accidental hero?" TV Tropes has the answers.
According to the site's home page, "tropes are devices and conventions that a writer can reasonably rely on as being present in the audience members' minds and expectations. On the whole, tropes are not clichés."
True, I suppose. But after wading through list after list of obscure tropes everything blurred into cliche for me. And that, I've decided, can be a helpful thing for a writer. So if you're thinking about adding a certain character quirk or a plot twist, it might be worth checking this site. Undoubtedly your great idea has been done and done and done.
The majority of contributors to this Wiki are clearly grounded in fantasy and science fiction and are steeped in the minutiae of their passions; further, books are not privileged. The children's book world can be a tad insular and old-fashioned (Think how long it's taken graphic novels to be accepted). TV TROPES is a fun escape from the cloister.