Storypath cards are a later variant of Whimsy Cards which were published in one form by White Wolf, and later by Three Guys Gaming. The version from Three Guys Gaming is a deck of 84 cards with 2 blanks. Unfortunately, I have not been able to find a copy. Thus, the most I can do is provide some quotes and links regarding them.
Selection from Brandon Blackmoor's Review of Storypath Cards from Three Guys Gaming on RPGnet:
Years later Lion Rampant became White Wolf, which released Storypath Cards. These had none of the fun of Whimsy Cards: dreary descriptions on dreary grey paper with equally dreary grey artwork. They were not delightful.
Three Guys Gaming's Storypath Cards owe much more to Whimsy Cards than to their namesake. Physically, the cards are similar to the old Whimsy Cards: rectangular card stock, neither coated nor laminated. On the face of the card, a short text description of an event is accompanied by a small B&W illustration. Lest you be misled, these are not collectible trading cards of the sort collecting dust in game stores far and wide. The real value in these Storypath Cards is in what's written on them.
Think of Storypath Cards as plot-thickeners. Typically, at the beginning of the roleplaying session the GM will let each player draw a card randomly from the deck. Each card has a plot twist or an event, such as "Mistaken Identity," which the player can use to creatively complicate the game. If the player uses the card simply to make life easier for her character, the card is gone and not replaced (unless the GM is being really nice). If the player uses the card to make her character's life more difficult, she eventually gets another card. The more fun and interesting she makes the game, the quicker she gets another card. Like Whimsy Cards, you have to use Storypath Cards to appeciate them. Once you get the hang of using them, it's a blast.
Not every game is appropriate for Storypath Cards, but most are. Even a deeply serious, grim and gritty mystery game can be enhanced with judicious use of Storypath Cards. And since the GM has final say over whether a player can use a card (or even what effect, if any, a card will have on the game), there's no unbalancing effect on the game.
Selections from the Storypath Cards Rules of the Four Colors al Fresco RPG by woodelf:
We have used Storypath Cards, by Three Guys Gaming, for play and in any examples. If you can find these, we heartily recommend them. They are a good mix of concretely mundane (Itch, Overheard Conversation), action-related (Unexpected Problem, Success!), and plot-oriented (Lost Hope, Shadowy Figure). If there is any flaw in these, it is that a few too many of the cards are mundane, and not enough are plot-oriented, so their affects tend to be less significant than you might desire.