I am myself aware of two alternate Wizard specialisations (sort of):

There's the Anagakok, which has a specialised unique list.

Then there is the Abyssal Specialist, which has a quite broad list of spells they are considered specialised in.

Because of all the nifty things that interact with specialised schools and the like, I would like to know if there are any other alternate wizard abilities that explicitly count as specialisation.
If you can think of ways to include more spells than intended under these umbrellas, even better.