Spider-Man Creator Makes a Cameo
In the scene where Spider-Man and Doc Ock are fighting on the clock tower, Doc Ock throws a clock hand at Spider-Man and it falls to the ground. When it hits the ground, we see two people moving out of the way to avoid being hit. One of the them happens to be the creator of Spider-Man, Stan Lee.
Other Cameos:
Bruce Campbell (played "Ash" in the "Evil Dead" films, as well as Brisco County, Jr. and others) appears as the rude usher to MJ's theatre show.
Scott Spiegel (writer of Evil Dead 2 and fiend of director Sam Raimi) plays the man on the balcony when pizzas are dropped there.
Reference to Spider-Man Co-Creator
There are two references to Spider-Man co-creator Steve Ditko. The first is that Peter Parker's landlord is called Mr DITKOvich. The second is that while Hoffman and Jameson are thinking up titles for the new villain, Hoffman suggests "Dr Strange", a superhero who was also co-created by Steve Ditko.