"Post Offices with Christmas Names. Interested customers can write to these Post Offices for postmarks to keep or to share with friends. Enclose a stamped, addressed card or letter in another envelope or box labeled “Christmas re-mailing” and address it to the postmaster of one of the towns listed below. Please allow enough time for postmarking, re-mailing, and delivery."

See it: http://about.usps.com/who-we-are/postal-history/christmas-post-office-names.pdf

Currently available pictorial postmarks of all themes - explore this (I prefer the PDF format)
http://about.usps.com/postal-bulletin/pb2011.htm

See older postmarks from my collection:

http://s289.photobucket.com/albums/ll201/dorincard/Postmarks/?albumview=slideshow

Various themes (or simple day cancel) on postmarks from around the world:

http://dorincard.blogspot.com/search/label/postmarks