Spidey 3 in interesting because it has great potential for fan editing. I may be in the minority here, but I think the first 2 films are ok at best and this one has some of the best story material so far (it was NOT a good movie, but it had potential to be the best). The black suit story was great, and the relationship issues Peter and MJ had were very mature and realistically handled (the idea of their competing egos - the superhero VS the starlett - was a great concept and was magnified by the black suit. Yes, the bar scene was over the top, but it was SUPPOSED to be - it was clearly done with a wink).
I can't agree that cutting out Venom makes sense because Venom is an extension of the black suit storyline. On the other hand, it was painfully clear that Sandman had absolutely no business in that film - his character has no affect on the main storyline and the stupid sub plot of him trying to get money for his daughter's hospital bills was laughable and pointless; again, it had no affect on Peter & MJ's story, which is the core of the film. In addition, the idea that HE is really the guy who killed Peter's father is just plain stupid and even THAT thread could be cut and all it will do is bring back more focus to the love triangle which is where the film needs to be.
If you cut Sandman and trim down the Harry's Goblin Jr scenes, I really think S3 would begin to shine. The best bits in the film are about Peter, MJ and the black suit so the more you stay true to that story the better the film will be. All the extra crap with Sandman and over-blown battles with Goblin Jr are pointless action that take you away from the good story trying to get out.
Of course, it would be easy to cut out Sandman from most of the film, but he's so woven into the battle at the end I'm not sure how it would work.
But it's DEFINATELY something I thought about while watching...
S3 bascially needs an "Attack of the Phanton" treatment. Bring it down to 1:45 mins and you might have a good movie in there...