Totally useless piece of fluff. Very few of the sites I frequent use it, but I suppose the genre has some bearing. OK if they put a 'skip intro' link (often almost invisible), but sites which don't do so immediately lose me as a casual visitor.
Turning off all 'active' elements in your browser will stop it from firing. Most active stuff is cosmetic anyway, with the possible exception of those annoying Java-only menus.