Still, when 3D is done well, it can be a magnificent addition to the cinema experience, same as sound and colour. James Cameron designed the whole universe of his Avatar to be a good fit to the strong points of the technology, and discovering the film in a 3D IMAX is still one of my fondest memories of the last decade.
So instead of interpreting the question as "Which classic title would you want to see re-issued and abused as a cash-grab", I'd like everyone to approach it more as "I remember this thing I saw as a kid and I always thought it would look awesome in 3D". Any classic that comes to mind, or just a cool moment? Something from the thirties, or eighties perhaps? An intimate indie, a nature documentary, a thriller?
Chime in, in the comments below, and HAVE YOUR SAY!
Oh, and that screenshot above? That is from Ali Billiman Jr.'s 1969 film The Stewardesses, allegedly the most profitable 3D-film ever made before Avatar took that crown.
(This also means I've sorta-kinda made a porn-movie joke already, so you won't have to, heh...)