We've run across some neat web apps in the past -- be it the Face to GIF app that lets you create animated GIFs with ease using your computer's webcam, or something a bit more practical like UT’s enlarging and denoising app. The ‘Average‘ web app definitely falls on the less-practical side of things. It allows you to easily combine any number of Flickr photos from a set or tag into a composite average of them all.
Without the process of manually, layering images over one another. This app compiles them all into one image that average's out just what the image will come out looking like.