Have you heard of Genius? It’s a cool website with the tagline “Annotate the world”—where users can annotate rap lyrics, videos, and (of course) novels. Consider it an even more hyper-focused version of Wikipedia, where you’re getting down to the granular level in discussing the inspirations and meanings behind all manner of text.
Where Genius differs from Wikipedia is in how a given excerpt—like, say, Lev Grossman’s novel The Magician King—can include notes and asides from readers and published authors. Like, say, Grossman himself.