While you're waiting for my next act of brilliance . . . ahem . . . I refer your attention to Ryan Britt's list of unfairly derided sf movies over at Tor.com. I more-or-less agree with his list, except I didn't see The Chronicles of Riddick but liked the set pieces, and didn't see Equilibrium but liked the idea, and I thought Superman Returns really did suxxor just like everybody says. I mean, seriously, Superman as fornicator who runs out on his illegitimate kid just does not work, nor does copying all the best scenes from the previous movies.
I do agree with his placement of The Island on this list, which Michael Bay tried to completely wreck with nonsensical action and misplaced humor, but failed in this instance, the result being forgettable but not awful.
Readers have naturally enough suggested additional titles in the comments (and, to my delight, trashed Superman Returns). One title I particularly concur with is Lost in Space, which is nearly swamped by its CGI but nonetheless captures the campy fun of the original.