(the easy way)
Bring a pot of water to a simmer, it should not be boiling. Place the tomatoes in the water until the skin just begins to peel, usually about 30 seconds depending on water temperature. Remove tomatoes from hot water and immediately immerse them in cold ice water. The skin will be falling off already, and you can easily peel off the rest of the skin with just your fingers. Since they were not cooked very long, the flesh is still firm and you can do this without making a mushy mess.