This entry has a common thread that everything is about different, thought-provoking visual stimuli.
The Denver Post posted this gallery by photographers from the Farm Security Administration/Office of War Information. These color slides were recovered from the 1939-1943 and show glimpses into what life was like for Americans during harsh times.
The data nerd in me really loves the blog Information is Beautiful for its use of data to create visualizations that are beautiful and interesting.
The science nerd in me loves the website The Fun Theory for the psychological experimentation it is conducting.