I'd like to see the ability to upload images in a large batch (i.e. several files at once), and also the ability to create galleries (folders with photos with a specific content).
Expanding on the gallery idea:
I'd think something with a automatically re-sized image in the middle, and thumbnails below. Clicking on a thumbnail will display the image (re-sized above), and clicking on the larger image would open a new window with the full resolution image.