Mac OS X only: Lightweight desktop application Xee browses all the images in a given directory with lots of features and keyboard shortcuts. Flip, rotate or zoom images, move back and forth from one to the next, run a timed slideshow or launch your editor of choice with Xee. Opening multiple files in Preview.app is one thing, but Xee is definitely an even better way to browse a set of images on your Mac. Xee is a free download, Mac only (universal binary.) Thanks, JakeZigler!