Keyboard shortcuts are useful for browsing through the hundreds of photos friends share in their Picasaweb albums. Picasaweb seems to be sorely neglected by Google when it comes to keyboard shortcuts. One can only move to the previous or next photo. Shortcuts to zoom in/out and pan on a photo would have been useful.
Next photo: Right arrow key / j / n
Previous photo: Left arrow key / k / p
I find the easiest to use are the left/right arrow keys to flick through the photos.