Those cards are a lot of fun. I'm sad I can't find a deck myself either.
I heard that PEG removed them as they were releasing the Savage Worlds Deluxe Edition which changed the rules slightly, but enough to invalidate the mechanics on several cards.
They may rerelease the cards with updated rules in future.
You can buy a deck of blank cards (system cards* are good) and write your own. Many of the cards are single-use edges, particularly Wild Card edges. Some give the each player another bennie, but give the GM an advantage at the same time (giant monster, reinforcements, etc.) Others are player-induced NPC actions (villain gives a monologue, distracting him.)
* System cards are also known as "index cards" in some countries.