Free Flash Image Viewer: AutoViewer
AutoViewer is a lightweight (11kb) & free Flash image viewer that displays the images horizontally.
It also works as a slide viewer with the play-pause-previous-next buttons and can be navigated both with mouse & keyboard.
AutoViewer preloads the images, so this application is more suitable for galleries with 30 images or less (pro version is optimized for more images).
This Flash image viewer‘s interface rescales to fit any aspect ratio images and monitors. And, galleries can be created via Picasa, Adobe Lightroom, a PHP script or manually.