The Iron Man-Iron Monger fight in the first one, and the entirety of the failed armor sequence in the second, are homages to similar scenes in RoboCop 2. The director even makes a comment on it on the second film's DVD commentary.
Iron Man 2
When Tony is drunk-piloting his suit, the partygoers first start throwing booze bottles into the air for him to shoot at. Then one of the girls shows up with a whole watermelon. Tony literally shouts out, "I think she wants the Gallagher!◊"
Self proclaimed comic book geek Howard Stern heavily promoted the first Iron Man film on his radio show, even interviewing director and casual friend Jon Favreau. In an interview on one of Stern's satellite radio channels during the promotion of Iron Man 2, Favreau confirmed that the foul-mouthed Senator Stern from Iron Man 2 was in fact a shout-out to his friend, the foul-mouthed non-Senator Howard Stern.