I learned an awesome trick yesterday while watching a chef interview for a chef instructor position with our company. Whenever I roast peppers, I do one at a time and I have to keep a close eye on them to make sure they don't roll off the burner. Well, not anymore!
If you have a gas stove, turn the metal rack over the flame upside down and then put the peppers over the flame. It provides you more space to roast more peppers at once and it creates a little basket to keep them from rolling around. Genius!