What can I do with lots of extra egg yolks? My passover baking is using a lot of whites!

Curds - lemon, orange, rhubarb. Egg yolks are great in them.

Custard too!

I also freeze them. Whisk them together, pour into a contain with a lid. Defrost overnight in the refrigerator. Use them as you would fresh yolks. This way you need not feel pressured to use the right away.

It's asparagus season and what is better on it than hollandaise? Or on some simple cooked fish or have yourself eggs benedict. Hollandaise is the bomb.

My daughter and her friend just made a key lime pie using four yolks.

Great ideas here. Or you can try this: http://www.food52.com/recipes/4057_hungarian_shortbread

Custard...check out some of the pudding recipes on this site. A lot of home-made ice cream recipes start with a custard base as well.

Another thought is whisking them into a salad dressing. Or a sabayon and egg bread also come to mind.

Aioli is the first thing that comes to mind. Avgolemono is another. Here's a link to a Squidoo article detailing ways you can use up your leftovers, anywhere from one yolk to 8 at a time: http://www.squidoo.com/eggyolkuses

cheers!