Off the top of my head....
Novels:
The Best and Brightest (featuring the first gay relationship in Trek)
Starfleet Academy (novelisation of the game, but fleshed out and pretty good)
YA novels:
Whole series of Starfleet Academy books about the TOS and TNG characters as cadets
A series of Kelvin Universe Academy books.
Comics:
DC did an Academy prequel special with Kirk and company
IDW did a limited series about new cadets in the Kelvinverse
There's a current series about Picard's time at the academy
And the Starfleet Academy game had a sequel, Klingon Academy starring Christopher Plummer in live-action video cutscenes.
Oh, and merchandise. I have a Starfleet Academy keychain which I've had for the better part of a decade.