I even remember one episode of DS9 when a stardate reference was thrown in delibarately for continuity reasons.
This was about the same time that "Generations" came out in theatres, in which Enterprise-D was destroyed. Very soon after that, Jonathan Frakes appeared as a guest star on Deep Space Nine, playing Thomas Riker (William's transporter clone from "Second Chances"). Thomas was posing as William in the storyline of that episode, in which he makes reference to Dr. Crusher letting him "away from the Enterprise" for a while.
I remember a lot of Trek talk boards being really confused by that -- the episode aired after Generations, but made reference to Enterprise-D still being around. The stardates solved it: the episode actually took place "earlier" in Trek-time than the movie, even though it was filmed later.