Night Sky Playing Cards
They won't do much to improve your poker game, but these Night Sky playing cards will give you a leg up on learning the constellations. Each of the deck's 52 depicts a sky full of stars with a different outlined constellation. Suits are also divvied up into winter, summer, spring, and fall to reflect when the constellation is visible (at least in this hemisphere).
Constellation names, pronunciations, and nicknames (e.g., Sagittarius, "the Archer") run along the top of the cards. In the bottom lefthand corners are images of what the randomly drawn connect-the-dots in the sky are actually supposed to represent.