PicLens and cooliris
this is one of the coolest addons i’ve seen yet. it allows pics to be expanded to full screen from many sites including flickr. it is a very cool add on and i suggest at least trying it out. It is made by the makers of cooliris, which is the coolest firefox addon made yet. it allows fully functional previews before actually clicking on a link.
check them out at http://www.cooliris.com/site/ these are available for multiple browsers, but have the most options on firefox