The Spider-Man series looks like one of the great movie franchises ever--so long as you ignore the trainwreck that was <em>Spider-Man 3</em>. You can find many folks who'll document what went wrong in <em>Spidey 3</em>, but almost nobody can tell you how to fix it. I can, in two words.
So long as we're talking about ways geeks could improve Hollywood, lets indulge in a little "What if...?" revisionist speculation.
Many have argued that Spider-Man 2 was the greatest comic book movie ever made, and there's some financial data to back up that claim. Combined with the first Spider-Man flick, the webslinger line looks like one of the great movie franchises ever--so long as you ignore the trainwreck that was Spider-Man 3. You can find many folks who'll document what went wrong in Spidey 3, but almost nobody can tell you how to fix it. I can, in two words:
(Warning, spoilers follow.)
Now, most reviewers will tell you that Sam Raimi wanted to do a Sandman-centered movie and studio/Marvel Comics forces rammed Venom down his throat. Thus, everything would have been better if they'd have just kept Venom out of it. I completely disagree. It was Sandman that needed to go.
The Sandman storyline needlessly retconned Uncle Ben's death and completely removed the poignancy of Spidey not stopping the thief that would eventually kill his father figure. As a result we get the mish-mash storyline of revenge by and against Peter Parker.
Here's how it should have gone down.
Harry Osborne wants revenge against Pete for killing his dad, Norman. He wants to use the Green Goblin tech to fight Pete on even terms, but he knows the Goblin Gas makes you insane. (A plot point completely ignored in Spidey 3.) Plus, Norman was smarter and stronger than Harry will ever be (in Harry's mind), so he'll need an edge.
Thus, Harry uses the last of his fortune to perfect Project: Venom, a symbiotic lifeform that feeds off emotion, regulating the psychotic tendencies the Goblin Gas induces, and converts that emotion into additional strength, speed, etc. With the combined Goblin/Venom powers, Harry should be able to defeat Pete easily. This also explains why the "new" Goblin is black and not green--the symbiote suit. It also avoids the pointless and stupid extraterrestrial origin of the symbiote, and makes it much more relevant to the Harry/Pete rivalry.
When Harry confronts Pete, just as happened in the real movie, Pete still wins, despite the power discrepancy. The emotional overload--rather than the idiotic "bump on the head" as in the real film--is what leads to Harry's subsequent memory loss. The symbiote flees Harry, taking his powers and his thoughts of vengeance with it. He is cleansed, literally and figuratively, of his rage against Peter. The symbiote is the tangible icon of that rage.
Said rage, incidentally, has found a new home. Lusting after Pete's power and tangled emotions over Harry, it follows Pete home, transforming him into Black Spidey, and allowing him to succumb to all his darker urges as both Parker and Spider-Man.
Meanwhile, a counterpart to Pete's civilian life--Eddie Brock--shows up, without any of of Pete's scruples. He lies, he cheats, he schmoozes, he stalks his girl (Gwen Stacy)--everything Peter would never do. Until, that is, Pete gets the symbiote, and he starts fighting on Eddie's level and wins. Hateful Pete alienates everyone--Mary Jane, Harry, Aunt May, Eddie--but his rage makes him powerful (a la the Dark Side) and he becomes successful if lonely.
Just when he has a chance to make right with Harry--after the symbiote has erased Harry's rage--Pete blows it by acting on all his hateful, selfish impulses towards Harry. Scorned, Harry's own memories and hatred eventually return. When Pete realizes what is going on, it's too late. He rejects the symbiote--renouncing his rage but becoming weakened in the process. Once again, nothing goes well or easy for Spider-Man.
Of course, the symbiote goes looking for someone that hates Pete as much as it does, and finds Eddie Brock. Eddie now has all the Goblin powers and Spidey powers it stole from Harry and Pete, plus all the memories. What is Venom's evil grin if not a hybrid of Spidey's mask and the Goblin's helmet? Venom also knows the one thing that means the most to Harry and Pete: Mary Jane. It kidnaps her, and Pete and Harry must join forces in their weakened states to defeat Venom. They literally put aside their rage and defeat it, for the sake of the girl they love.
Harry still buys it, and thematically Venom should, too. The personified hatred was defeated, if at a painfully high cost. This ends the Harry/Pete storyline, brings closure to the movie trilogy, and leaves plenty of villains and plots for the franchise to carry on depicting. (Like, say, Sandman.) Of course, that isn't what happened, and we're all the lesser for it.