trick decks

I'm making an "Assassin's Deck" of heckler killers, what are some of your best to write on cards?

So let's say you carry several decks of cards to your gigs. A couple of regular decks, maybe a Svengali and a Brainwave deck, and a Si Stebbins stacked deck. Does anyone have a method of labeling these decks so that you know one from another? I've noticed some magicians used several deck...