Using Wold Newton
as a guide, it appears that Greg Cox made several nods to spy fiction of that era.
Also there have been comic crossovers with X-Men, Legion of Superheroes, Dr. Who, Infection...
Now, is there a possibility that Star Trek actually shares the universe with these?
The comic ones can be explained away as a crossover between parallel universes, but what about series like The Avengers, Man from UNCLE, Pretender, ...
Could these also have happened on Star Trek's Earth? Or were they only easter eggs, showing that something dis happen, but not necessarily what we have seen on screen?
By the way what other fictional works could have happened in Star Trek? Well we can say with a 99.9999% definitiveness that StarGate (at least not the TV series, the Movie could have happened), Blade Runner, Alien+Predator could not have happened.