Gil Kane did a number of covers for Iron Man during 1971-72. Here are four of my favorites:
Iron Man #44 really sent chills down my spine when I first saw the creepy Night Phantom, but it's the expression of horror on the face of Stark's girlfriend Marianne that sells the cover.
Iron Man #45 brings back memories of the Vietnam anti-war protests on many campuses around the United States. Many Marvel heroes had a "Crisis on Campus!" issue, this was Iron Man's turn.
Iron Man #46 has the Guardsman setting Stark's armor on fire--right in front of Stark Industries. It's really humilating to be defeated in front of your own co-workers. I really like the inking on this cover.
Iron Man #54 gives us Kane's view of a fight with the Sub-Mariner. Namor always works best on a cover when he's launching out of the water to attack his opponent. Bob Layton did a commission where he re-interpreted this cover, you can probably find it on his website. Nuff said.