Brain Drain
In this free online game from Hyper Gurl, you'll need to turn over pairs of cards before the timer stops ticking. You'll click on the cards (playing cards) and attempt to turn over pairs. Pairs are cards with the same number, regardless of suit, and the joker cards. The online timer keeps track of your time for the current game as well as past games, so you can play this game repeatedly and see if you beat your best score.
The Coin Game
This game idea from Empowering Parents requires players to pay close attention to detail in order to remember the sequence of coins. You'll need several different coins, such as pennies, nickels and dimes. Younger players will want to lay about five or six of them on the table in a row and try to remember the order in which the coins were laid. Cover them with a piece of construction paper (so you can't see through it) and jot down the order the coins were in on a separate piece of paper. Remove the construction paper and see if you were right. Adult players may want to start out with eight or nine coins.You can challenge yourself by adding more coins. You could also play this game with a partner and see who manages to remember the most coins correctly. For even more of a challenge, have some of the coins show "heads" and others show "tails," then require players to remember the order of the coins as well as which side was showing.
Concentration Flash Cards
You can make this concentration game from Kaboose to coordinate with seasons or holidays. You'll need 20 3-by-5-inch index cards to start. Cut each card in half so that you end up with two squares from each card for a total of 40 cards. On each card, draw a holiday-related design. For instance, if it's close to Christmas, you may want to draw Christmas trees, wreaths, ornaments, snowmen, stars, candy canes, holly leaves and stockings. You'll need to draw two of each picture so that each design has a pair. Depending on the age of the child, you can start out with anywhere from 10 to 20 cards. Turn the cards over so the design isn't showing, then have kids try to find as many pairs as they can in one minute. If you want, you could also use holiday-themed stickers or stamps instead of drawing the images.