[QUOTE=lizardling]
Ooo. I have most of a box of eggs, and this thread is making me want to try. However I’m slightly worried that I’ll end up giving myself no end of misery if I screw up mayo or hollandaise sauce. I’ve never made either, and from what I understand, it takes practice to make either, right?
Also, I’m trying to stay out of the gutter, here, and all y’all aren’t making it easy. 
[/QUOTE]
Mayonnaise is easy. Just requires patience. Hollandaise is more finicky, but there’s easy ways of doing it with a blender. (Just google “blender hollandaise.”) You can also make mayonnaise easily with a blender.
The basic rules are as follows:
For every egg yolk, you’re going to need about 1/2 cup of oil. I use a half and half mixture of extra virgin olive oil and neutral vegetable oil.
So, let’s do it with two egg yolks and 1 cup of oil:
Put the egg yolks in bowl. Beat them with a whisk or electric hand-held mixer until the yolks thicken and turn lemony yellow. Now, here’s the important part that requires patience. For the first third of a cup or so, you have to add the oil very very slowly. I start a couple of drops at a time, then move up to teaspoonfuls. Put in a couple drops, mix, and don’t continue until you see that all the oil has been absorbed by the yolk (you can tell because it will look homogenous), then add more. After you get 1/3 or so done, you can start adding in a slow stream, whisking constantly. If you see oil starting to pool, just hold off on the oil, whisk it together until it looks homogenous again, and continue.
You’ll only screw it up if you try to rush it. For a cup of mayo, it takes me 5-10 minutes to whisk by hand. I’m probably a little slow, but I’m extra cautious and have never had a mayonnaise break on me.
As for the extra ingredients (usually, for me, lemon, a little dijon, salt, pepper), I start adding those slowly about a third of the way through, or I just dump them in at the end. The usual method is to start with your lemon, yolk, and salt beaten together at the beginning. To be honest, I really can’t tell any difference in flavor between when I do it at the beginning, or if I do it at the end. To me, it’s easier to do it at the end because I can correct the flavors much more easily.