A modern element to some RPG's now are cards. They have certainly existed in RPG's before but they have gained popularity in more recent years. I cards from the Star Wars RPG. Twilight 2000, Alien and the Carbon Grey ones which are pictured above.
I wasn't sure of their use, more so how their use would add or improve the gaming experience. I have found however that they can be quite useful. The Star Wars cards cover NPC's and are great when a GM needs a stat block on the fly.
Alien was the first all round package. It includes cards for equipment, agenda's, npc's. During play these were useful for both GM and players. The Agenda's reminded the players of their motivations. The gear cards were great for having stats on hand without having to look in the book. Especially for disposable gear and items that the character will not be used on going.
Carbon Grey is the latest game that I have received cards in. Carbon Grey has cards on NPC's, beasts, vehicles and weapons. They have sped up some of the book keeping that would normally be done by flicking through pages in the book. Overall the addition of cards to the games have been a positive experience for us.