Photos Flickr provides for basic browsing of a Flickr photo stream from within a WordPress blog.
NOTE: This plugin is far from fully baked. You will need to be comfortable with template hacking in order to customize this plugin to look good with your theme.
My approach has been to write functions that you can call from a page template to print out either image index information, or image information, much like WordPress is either displaying an index of posts, or an individual post.
There are hooks for the full image index, an index of photo sets, set indexes and tag indexes, as well as pagination. There is no support yet for collections. Numerous bugs and ugly code are found throughout.