I am continually fascinated by the lush and nearly endless variety of styles and idioms in popular music, which attract devoted, attentive listeners to greater and lesser degrees. While I stand by my assertion that "genre" is mostly a fiction invented by those seeking to better commodify music and identify and target demographic groups (as amply demonstrated, I think, in this podcast episode--short version, it's mostly a continuum and spectrum within broad stylistic practices), there are common aesthetic or other features to be found within even the most nit-picky sub-sub-sub-genre distinctions.
A really great user post on reddit recently hipped me to the sub-genre and culture of Shoegaze (sub- to alternative rock, so technically a sub-sub-genre of rock, I guess). It's hard to write about music well, and the author of this post vividly describes what traits make up the sound world of this kind of music, and provides an in-depth timeline of its evolution with listening examples, lists sub-sub-(sub-)genre practices with specific albums/artists that typify them, and for good measure adds links for further reading.
It's a great post and a wonderful demonstration of one of the things that I most love about the internet, and one of its most disruptive aspects: people sharing their passions and knowledge freely, simply so others may also enjoy what they have found valuable and rewarding.
Seriously, check it out.