Infinite Crisis #5 contains an image of Kal-L holding the recently deceased Lois Lane, an image that harks back to IC's predecessor, Crisis On Infinite Earths. In issue #7 of COIE, Earth 1's Supergirl, the original Kara Zor-El from Krypton and cousin of Superman, died in battle with the Anti-Monitor. The cover of that issue became an instant classic:
A competition was held in the Week 40 of the weekly series 52 that followed Infinite Crisis where readers could vote for their favourite DC cover. The results were released in Week 47 and, by a "surprisingly overwhelming margin", the cover to COIE #7 came out on top.
Over the years, various DC comics would pastiche the cover of COIE #7 and those that I have found are shown below. If anyone knows of any more, mail me at jigsawmen [AT] googlemail [DOT] com and let me know.
Peter David (who wrote Supergirl #79 and Fallen Angel Vol 2 #16 mentioned below) wrings out another pastiche in this page from Young Justice #35.
The cover of Uncle Sam And The Freedom Fighters (Vol 2) #8.
A page from Justice Society Of America #9 featuring the Kingdom Come Superman holding Starman.
A page from Adventures of Superman #649, a tie-in with Infinite Crisis.
Firestorm #21, a tie-in issue with Infinite Crisis.
Superman: The Man of Steel #10
Fallen Angel Vol 2 #16 - ironic as this non-DC series is written by Peter David who wrote Supergirl #79 mentioned above.
Uncanny X-Men #136 which, cover dated August 1980, actually pre-dates COIE #7
The final page of Final Crisis #6.