I know of a lot of little more obscure chans including a whole series of ones that died over the years. Apparently 7chan still lives which amazes me.
And yeah the smaller spin offs are pretty amazing how small or niche they are. Usually what happens is either a mass ban wave or board closure causes a bunch of people (usually the cancer) to seek a new refuge where they can continuing being butthurt at their parent board. This is exactly how both 7chan and 8chan got created, where 7 was from mass bans, and 8 was made specifically because moot killed /new/ and /r9k/ because both those boards were shit. >>18969
We all know those boards. Britfa.gs was basically involved in creating KC and due to KC everyone got to know all the other international shit boards including 55chan which you neglected to mention, along with dvach/sosach, yilauta and kavalauta and so on or magyarchan or any of the other numerous smaller boards from some countries like the Italian one and Spanish one that probably doesn't exist. Or all the numerous raid chans like rockstarchan, 711chan, 888chan, 315chan, or whathaveyou. Or tiny places to find ebooks like zerochan and freechan. There was a place called over chan that also tried to catalogue them, and a porn one called fapchan iirc, and operatorchan for example which was basically just /k/--the chan. There's been hundreds of IBs coming and going over the years.