Is it really important to let meat rest before you cut it?
When meat comes off the heat, it is soft and more difficult to carve in nice even slices. More importantly, though, when you cut just-cooked meat, you lose more of the juice. When you let a steak rest a few minutes, or a big roast rest for a half hour, you will lose far less juice when you cut into it.
Recipe: Salt-and-Pepper Beef Roast