We have these flashcards and LOVE them:
It started out with Luke just carrying around the ball card - as that was (and still is) his favorite word. Now we play games and so far he can point out the ball, dog, cat, shoes, bear, keys, car, mirror, and baby. It's a lot like his picture books, but these he can actually find and then hand to me. They make other sets that I think we'll be ordering soon. I highly recommend them!