I was going to say mayonnaise to go on a nice fresh salad! You could flavour it with garlic, chives, or tarragon -even chopped chili - whatever takes our fancy.
Or a baked egg custard to go with some stewed summer berries - yummy
Why not just freeze them until needed (within four months or so max)? Put one each in an ice cube tray and when frozen place them in a freezer storage container or bag. Be sur eto lable them for date. Another tip is to stir them together (before freezing) and add 1/2 teaspoon salt to every 4 to 6 yolks (about a cup full)... Mrs. C says this keeps them from clumping when you use them. If the prospect is to use them in a dessert type recipe, replace the salt with about 1/2 teaspoon full of corn syrup per six yolks...