If you want to freeze the yolks you can. You have to add either salt or sugar to them though. If you add sugar it's 1 TBSP of sugar per 1 cup of yolks and if adding salt you add 1/2 tsp salt per 1 cup of yolks.. then just freeze them in ice cube trays. One large yolk is a wee bit more than 1 TBSP of yolk. I usually do 2.5 TBSP of yolks per ice cube and call it 2 yolks.

I use them for custards, puddings, sauces, curds.. there's TONS of things to do with them.