I was playing around with Astro file viewer and found a hidden gem!! Hidden with it is a fantastic app called "Astro Image Viewer"! To use it, you use the file-viewer to navigate to a directory (camera, downloads, etc), then tap a photo and chose "Astro Image Viewer"!
It has swipe-to-browse viewing (swipe left and right to change images)...
It ALSO has really cool rotate gestures enabled, so if you draw a clockwise half-circle, it rotates the image clockwise 90 degrees!
(there's also a 'filmstrip' along the bottom with kinetic scrolling)
It's not perfect (no zoom), but it's great for flipping through photos!