Monster cards are handy. One of the guys in our group used the D&D minatures (which come with stat cards) in a game he ran. It made it very easy for him to consult monster stats because he had them right there, without having to crack open a single book. 1st edition Earthdawn did this as well and I've found in quite handy when running that game.
You know, monster cards would be useful, especially if you had all the rules stuff on it and then a book and page reference. That way most of the time you would only need the card, but even if the monster was detailed in a supplement it would be quicker to find.