While I do realize that DT is not an image editor, I would nevertheless like to propose the inclusion of two image display options: scaling and rotating.
The main motivation for scaling is that many pictures on Web pages that are low-resolution but scaled to a larger size by the HTML code become nearly invisibly small dots after copy-pasting from Safari. It would be nice to be able to scale them up again.
The main motivation for rotating is photo management. DT is quite nice for managing photo archives (I gave up in iPhoto because it doesn’t offer hierarchical albums), but I don’t like having to turn my head (or the screen) to look at photos taking in portrait mode. Note that I don’t want DT to do anything to my image file, but just display it rotated.