Left-Handers Day dates back to 1992, founded by the Left-Handers Club. Enjoy your day, lefties, and be happy you live in a time when left-handers aren't forced to convert.
Obon is a Buddhist tradition observed in Japan either in July or August, depending on whether the solar or lunar calendar is used. Regions of Japan that follow the lunar calendar observe Obon from August 13th to August 15th this year. Celebrants hang lanterns in front of their homes to welcome their ancestors' spirits to visit. At the end of Obon, those lanterns are floated down rivers or out to sea, to guide the spirits back to their world.
Raksha Bandhan takes place on this date in 2011. Based on old stories of India, wives made lucky amulets for their husbands, called rakhi. The tradition has evolved into a brother-sister celebration, in which sisters show love for their brothers by giving them rakhi.
The Central African Republic observes Independence Day on August 13th.
August 13th is National Filet Mignon Day. This has to be one of the best foodie days ever created, unless you're a vegetarian.