Mutants
I'm still not going to write up my full comments on X2 yet, but I've been meaning to post this link for a while: The Rocky Horror Mutant Show, by Alison Knapp and Shoshanna Green. Yes, it's a feature-length filk opera: full filks of (I think) every song from The Rocky Horror Picture Show, used to re-tell the Phoenix saga from the X-Men comic book. But it probably won't make any sense if you haven't already read that storyline in the comic book (and you probably won't enjoy it much if you haven't seen Rocky Horror). And if you haven't read the comic, RHMS probably contains major major spoilers for the next X-Men movie, X3 or whatever they're going to call it.
But one thing I can say without spoilers is that I was always fond of Scott "Cyclops" Summers in the comic book; RHMS was my first contact with the idea that he was a total whiner. Which is one of the reasons that I kept thinking of RHMS all through X2. I don't like him much in the movies.
The other reason I kept thinking of RHMS was a particular line that ran through my head every time a particular special effect made an appearance. But I can't say more without spoilers, so I'll save that for my review.
There's also a sequel to RHMS, titled Schlock Treatment. I haven't seen Shock Treatment (the Rocky Horror "sequel"), and the X-Men storyline covered in this sequel didn't interest me nearly as much as the Phoenix story, so Schlock Treatment doesn't work nearly as well for me. But it still has some good jokes in it.