These symbols are from the FHWA proposed figures for the 2009 edition of the MUTCD manual. I used CorelDraw and PhotoImpact to generate the files needed for this slideshow.
Possible future signs if approved for use in the 2009 edition of the MUTCD manual. I selected some of the newer symbol signs which look interesting.
"The Federal Highway Administration (FHWA) publishes the MUTCD, which contains all national design, application, and placement, standards, guidance, options, and support provisions for traffic control devices."