I just loved playing memory when I was a kid. Playing it in the foreign language class has loads of possibilities- from the simple -matching two of the same pictures- to the more challenging- matching a picture with a word, or matching two parts of a sentence. As children have more experience with the language, you could have them match pronouns with appropriate verb conjugations (yo + hablo) or matching gender (la + flor).
When I play with my kiddos, I give it a twist. Using a pocket chart, I have taped the numbers 1-20 on the chart, spacing them so the cards can go between the numbers. The playing cards (I make them using clip art from google image search or flashcards) go into the strips of the pocket chart. To play, one kid has to say a number out loud (in Spanish, of course) in order to have me turn the card over. A second kiddo says a second number, upon which I turn that card over. If they are a match, yippee! (or yupiiiii, as the case may be) If not, I flip them over and two new kids get a turn and so on. At the end of the game (usually I allot a specific amount of time to play), we count the number of pairs and say each pair outloud. This way of playing is a great way to get two for the price of one- practicing numbers while at the same time practicing target vocabulary on the memory cards themselves. ¡Disfrutelo!
