I just wrote this all out in an email to my mom, so I thought I'd cut and paste it here.
the basic pesto recipe from The Moosewood Cookbook
3 cups packed fresh basil leaves
3 to 4 large cloves of garlic
1/3 cup walnuts or pine nuts
1/3 cup olive oil
1/3 cup parmesan
Blend it all up in the food processor and toss desired amount with hot pasta. As a variation, you could use part spinach and part basil. I like to add fresh parsley when I've got it. I've also varied the nuts. Sometimes I use 1/3 to 1/2 cup of tahini instead of the nuts.
For parsley pesto, do the same thing. Substitute parsley for the basil and almonds for the nuts. Add one can of anchovies and some crushed red pepper to taste.
For cilantro pesto, do the same thing. Substitute cilantro for the basil. Substitute almonds or tahini for the nuts. Add the juice of one lime and some crushed red pepper to taste. Use less olive oil, maybe 1/4 cup.
Now that I've made a lot of pesto, I make it a little different every time- mainly varying the type of nut or nut butter, depending on what is in the house at the time. I also add 2 tbsp of flax seed (not ground) to every pesto mix now, as nutritional fortification. When I eat it, I like to add a little vinegar to my own portion.
I like the cilantro and parsley pestos the best and it's easier to find those herbs (fresh and in large quantities) in the store when the basil is out of season.