I'd have loved there to be an "Unbreakable 2," though I hardly agree with the premise that the first film was merely getting the origin story out of the way.

Another one that belongs on the list: "Gigli II"

Now, that might have been interesting!

Gronk.

AThere are a number of Arthur C Clarke's novels that would make interesting movies - Childhood's End, A Fall of Moondust, Songs of Distant Earth, Imperial Earth....