Spider-Man Creator Makes a Cameo
When the Green Goblin makes his first big appearance and bombs the balcony (which has Mary Jane and Harry on it) we get a split second look at some people ducking for cover. One of those people is the co-creator of Spiderman, smiling Stan Lee.
Other Cameos:
Bruce Campbell (played "Ash" in the "Evil Dead" films, as well as Brisco County, Jr. and others) appears as the announcer during the wrestling match.
Ted Raimi (Sam's younger brother, who played Henrietta in "Evil Dead 2") shows up as Hoffman, a staff member at the Daily Bugle.
Lucy Lawless (who played Xena: Warrior Princess on TV) pops up as a punk rocker--she says "Eight arms? Sounds exciting."
"The Classic" (Sam's yellow 1973 Delta 88 Oldsmobile Classic, or at least one of its six body doubles) as Uncle Ben's automobile.
Sam Raimi (director of the film) himself flashes onto the screen sipping some coffee and talking into a cell phone as Spider-Man flies past him.