Ever since Katharine Hepburn hooked up with Spencer Tracy, Hollywood producers have lived by one commandment when casting: When chemistry works, don't change it.

The latest example is the upcoming comedy 'TMI,' which re-teams 'Just Friends' and 'Waiting' co-stars Ryan Reynolds and Anna Faris. In movies, of course, familiarity doesn't breed contempt. It breeds sequels.

So here are few on-screen couples who, for better or for worse, we'd like to see hook up at least once more-and what it might look like.
categories Movies, Hot Topic