velvety egg yolks

The method I use is one I picked up from Thomas Keller. Break each egg into it's own ramekin. Cover with white vinegar. Let rest for five minutes while you bring your water to a boil. Reduce heat to a steady simmer. Using a wooden spoon stir vigorously to create a vortex. Quickly drop your egg into the vortex. Cook for 2 minutes. For a slightly firmer yolk cook for an additional 30 seconds. The combination of the vinegar and the vortex will cause the white to ball up around the yolk for a nicer presentation.

I use two different methods in Denver. One is to submerge the eggs and bring to a boil. Immediately cover, turn off heat and steep for 4 minutes, then rinse in cold water. The other method is from Cooks Illustrated which also did some crazy experiments- some involving shaking the eggs like crazy (here's an interesting read if you want more: http://www.nytimes.com/2012/10/14/magazine/cooks-illustrateds-christopher-kimball.html?pagewanted=all)

"Bring 1/2 inch water to boil in medium saucepan over medium-high heat. Using tongs, gently place eggs in boiling water (eggs will not be submerged). Cover saucepan and cook eggs for 6 1/2 minutes.

Remove cover, transfer saucepan to sink, and place under cold running water for 30 seconds. Remove eggs from pan and serve, seasoning with salt and pepper to taste. "

The Food Lab at Serious Eats did a project on perfectly boiled eggs, both soft & hard. Here's their 'recipe':
http://www.seriouseats.com/recipes/2009/10/perfect-boiled-eggs-recipe.html

Here's the science behind it all,
http://www.seriouseats.com/2009/10/the-food-lab-science-of-how-to-cook-perfect-boiled-eggs.html