These two Japanese websites have pretty nice tools for visualizing picture posts in big chunks (à la archive; but without other types of posts mixed in and without month breaks):
http://pics-search.info/tumblr — Lists all picture posts of a user chronologically, with a tag cloud at the bottom. Clicking on tags or searching for a username together with a tag lists all picture posts of a user with that tag. The website itself seems to have a number of other picture visualization tools as well.
http://tmv.proto.jp — Same as above, but doesn’t have the tag search box (but you can just enter the tag in the url-box). Can list picture posts with random order, also has endless scrolling. Also has a “similar users” feature.