I've started working on the next big update.  In the next version, you'll be able to group your favorites into categories.  You'll be able to import and export whole categories (instead of one picture at a time like in the initial release) and you'll be able to export all of your favorite images.  This should be a good way of sharing groups of images with friends.  I'll also try to add a slideshow feature that will let you view all of your images from a category (or all your favorites) one at a time (either manually advancing the images or cycling through them on a timer).