Fenix - The Burning Phoenix's Den
This is my best friend Fenix's site! We're both building our sites together bit by bit, so just like there's not much stuff here, his site is also a work in progress. You should check it out anyway!

Franzeska - OlderThanNetfic
Franzeska is a fairly recognizable name if you run in the circles that were once the LJ slash circles and that later became the early Ao3 scene. I particularly like her meta posts about fan culture. Even when I disagree with her, I find she puts forth her arguments in a very concise, intellectual way that doesn't get bogged down in using meta as a tool to bludgeon other fans. You may have seen I didn't get my education from slash. Why should you? or many of her other Tumblr posts about the fandom culture that has formed in the past decade or two on sites like Tumblr and Twitter. More recently, I particularly enjoyed this post about the recurring issue of people who assert that fandom "doesn't care about female characters" while they are in a fandom space that was created by and for m/m slash fans.
In the past few years, her blog has shifted to mostly contain these sorts of anon asks. Sort of like a 'Fandom Secrets' account combined with an Anon Meme (though most recurring repliers aren't anonymous, since you can't comment in the replies anonymously on tumblr, only send a whole new ask.) I find OTNF to be one of the few lurkable places with ongoing fandom discussion that doesn't make me want to cancel my internet connection.

Fujoshi.info
This site's URL speaks for itself. I really appreciate having a single site I can point to when someone starts saying dumb shit either about the etymology of the term "Fujoshi", being a weird racist about Asian media, or just has the (stupid) opinion that m/m content should be restricted to only being created and enjoyed by mlm.
Even if you're already educated in the realm of the BL genre and the history of m/m shipping, I still recommend giving it a quick browse. There are a lot of interesting texts and videos surrounding fan culture, and I like that they delve into the very direct connection between transphobic propaganda and anti-fujoshi campaigns in English language fan spaces.
When keeping in mind the connection between anti-fujoshi sentiment, blatant conservative-flavored misogyny, and bigotry against transmasculine people, the common threads between popular talking points against non-men enjoying m/m fiction reveal themselves as very obviously in service of extremely harmful and regressive ideologies about sexuality and gender identity.

Neverending Romance
A Bulbagarden forums-hosted site I remember fondly from my early days in fandom. It is an attempt to categorize all of the very imaginative ship names used in Pokemon fandom.
Pokemon fans tend to use punny names like Rocketshipping or Palletshipping or ColdCoffeeshipping. As you can guess, it could get hard to remember the names, or if you decided to ship something indipendantly, you'd have to search and see if anyone else had already coined a ship name. This site made it a little easier to keep track of the unending combinations of characters.
It seems silly, but in a canon like Pokemon where some people are using the original Japanese names for characters (especially before a game's official release) and some people are using the names in the English, Spanish, etc., version, having a standardized ship name that doesn't require using the characters' actual names can be very helpful.