Well, in the scene where Mystique is stealing the computer records, if you stop-frame it when the computer screen is shown, you can read all the names displayed there. Every name is of a mutant that has appeared in one of the comic books. The file folder names are significant too!
When Mystique is in the bar, on the TV playing in the background you can see the name Dr. Henry McCoy. Henry ("Hank") McCoy is the mutant known as The Beast, one of the founding members of the X-Men (in the comic book).
Hiding the following because it contains spoilers!
The fluctuations in Jean Grey's power at the end were very significant; it was the start of a storyline that in the comic books is called The Phoenix Saga. Basically, Jean didn't die at the end of the movie; she returns with vastly increased powers, and is re-named The Phoenix. It doesn't go well, because she starts to go out of control and has to be stopped by the X-Men. That's how the story went in the comic book, anyway.
Most X-Men comics today I would rate at PG-13 or even R, so you might want to wait a while before getting any for the Jedis to read. The older ones would be ok, but most of them are pretty expensive collector's items, now.