There are innumerable gallery and image slideshows applications and plug-ins, but very few show the images enlarged or full screen. With the 8 megapixels and above that most digital cameras have by default nowadays, lot of image detail gets lost.
JQuery has a great plug-in called SuperSize to show images full screen and fill up the browser window. Take a look for yourself:
View Photo slideshow
Pics are located on Google Storage Beta service for fast loading.