Snakes On A Plane 2: Snakes On A Train
Starring: the entire TGIF lineup from the 90's.
Plus the casts of Full House and Perfect Strangers, minus the Olsen twins.
For the record, the reason they can't just stop the train is because some kid has cancer.
Edit: This is an open thread, so hop to it, damn it. There are possibilities here.
Edit:
Jurassic Park kind of sucks, too.