Pairs is a free print-and-play game from Cheapass Games. You can also purchase printed editions of the game at the same site. From the publisher’s description:
The Pairs deck contains only the numbers 1 through 10, in a triangular distribution (1×1, 2×2, 3×3, and so on up to 10×10). The basic goal of Pairsis to avoid getting a pair. Your odds will depend on what cards you hold, and which cards you have seen! Scoring pairs earns you points, and the first player to reach a target score is the loser.
Minute Diktator is a free print and play game in which two players vie to get the support of the “Council of Five” to replace the departed Dear Leader.
FIKA is an 18 card print and play game in which two players try to win rounds by selling coffee, tea and pastry. It comes with a solo mode. From the BGG description:
Players must use the actions and goals on their cards and the cards in the FIKA supply in order to outsmart their opponent. The player that can win two rounds by getting the maximum value out of his cards, wins the game.
I like these mini games. They’re easy to print and assemble, and for a couple of bucks worth of ink and paper, I can get a nice filler game.
Zany Zoo is a two player print and play card drafting game. From the author’s description:
Zany Zoo is a 2-player card drafting game in which you select a total of 12 multi-use cards over 3 rounds. The cards can be used to build your creatures, feed them, or clean up their wastes. Build creatures with compatible parts, anticipate your opponent’s strategy, and manage your sanctuary well to win and be recognized as the ‘best zoologist of the third dimension’!