Giving a tatoo to an animal who doesn't have a choice in the matter borders on animal abuse, in my opinion. The same goes for the idiots who are piercing kitten ears with heavy earrings to make them into "gothic cats". Wrong, wrong, wrong!
I've been to two or three cat shows before...they are interesting and can be entertaining. It's cool to see the different breeds of cats and how they are judged in the show ring. Some of the breeders can get pretty territorial with their show cats, but a few of them are nice and will answer your questions about their cats. It's a good experience to go to one, even just as a spectator!