I’ve been seeing a TON of memory/matching games popping up all over the blogosphere. The great thing about these games is how customizable they are. I grabbed the ones from my bookmarks and searched for a few more to bring you these:
Bottle caps memory game from Crafty Beats

Juice cap memory game from Row of Ducks

Paper and woodchip memory game from Creative Chicks at Play

via Crafty Crow
Sounds memory game from Zrecommends

Shells memory game from The Write Start

Family and friends memory game from Chasing Cheerios

Quick and easy (and low cost!) memory game from Croqzine

Fabric memory game from Inchmark

Via Crafty Crow
Art cards memory game from A Bit of This and a Bit of That

Printed fabric memory game made by Under Construction (originally from the Stitched In Time book in left sidebar)

also seen at Sew Liberated from Meg who posted some great tips on playing the game with little ones.
Plus, Jennifer Ackerman Haywood, of CraftSanity, showed hers off on a local news show and talks about how to make it in this video
A few other ideas include using images from a favorite picture book (simply make a high quality copy of the original to make a pair) or make a game using fine art cards.