In FOOD SAFETY TIP #4: Raw Egg Yolks, I wrote how to store raw egg yolks. Freezing them doesn't work well.
While raw egg yolks don't keep very well, cooked egg yolks can be kept for a bit longer (and are generally more useful to have around).
If you have several yolks and not enough time to make one of our recipes, the drop yolks, one at a time, in boiling water until they become hard cooked.
You can then keep them in the refrigerator to use for slivering over creamed dishes, salads, or vegetables.
You can also freeze them but they get very mushy and not pleasant in texture.