Click on any image to see a full size version.  The picture will open in a new window.  If you leave the new window open and switch back to this page of thumbnails, the next thumbnail you click will open in that same new window, although it may remain behind the thumbnails until you manually switch windows.  Alternating back and forth between these two windows is the fastest way to look at multiple pictures.  In Windows, the alt-tab key combination will alternate between two windows.