Friday's celebrations

April 29th has a bunch of celebrations to consider:

National Arbor Day (last Friday of April) The first Arbor Day was held on April 10, 1872
International Dance Day
World Dance Day
National Shrimp Scampi Day

National Dream Hotline
Sense of Smell Day
Moment of Laughter Day

National Hairball Awareness Day (always the last Friday in April)
Zipper Day: Gideon Sundback, a Swedish-American electrical engineer, of Hoboken, N.J. designed the modern zipper (1913).

The National World War II Memorial opens (on April 29, 2004 in Washington, D.C.), providing recognition for the 16 million U.S. men and women who served in the war. The memorial is located on 7.4 acres on the former site of the Rainbow Pool at the National Mall between the Washington Monument and the Lincoln Memorial. The Capitol dome is seen to the east, and Arlington Cemetery is just across the Potomac River to the west.

Rodney King trial verdict announced, 1992 / Riots erupt in Los Angeles and surrounding areas
Cyclone kills 135,000 in Bangladesh, 1991
Nixon announces release of White House Watergate tapes, 1974
First flight by African-American Astronaut, Col. F. Gregory (1985)
Birthday - Dale Earnhardt (racer)

Birthday - Jerry Seinfeld Birthday: 1954 (Happy 57th!)
Christian Feast Day: honoring saints
St. Catherine of Siena's Day (patron of Italy; against fire)
The ninth day of Ridván (Bahá'í Faith)

Marriages Permitted Again - April 29th; In the Middle Ages, marriages have been frowned upon during Lent and thought to be unlucky, but were permitted again after Easter Sunday under the old calendar. Since May marriages are unlucky ("Marry in April when you can, Joy for maiden and man; Marry in the month of May, You will surely rue the day" according to an old rhyme), take advantage of the last days of April if you're in a hurry to tie the knot!
National Persian Gulf Day (Iran) 

Cassé Canari ou Wèt mô nan d'lo (Haiti)

The beginning of Arita Ceramic Fair (Arita, Saga, Japan)
Shōwa Day, traditionally the start of the Golden Week holiday period (Japan)

Emperor's Birthday (Japan) 

Midori no hi (Greenery Day, Japan) Between 1989 and 2006 it was celebrated on April 29th. In 2007 Greenery Day was moved to May 4th. The present observation of Greenery Day as a national holiday in Japan stems from the celebration of the Emperor Shōwa's birthday on April 29th every year during the Shōwa era. The name of the holiday was changed from "Birthday of the Emperor" to "Greenery Day." As its name suggests, it is a day to commune with nature and to be thankful for blessings. The day was renamed to "Greenery Day" to acknowledge the controversial wartime emperor's love for plants without directly mentioning his name. However, in practice it is seen as just another day that expands the Japanese Golden Week vacation. In 2007, Greenery Day moved to May 4th, and April 29th was changed to Shōwa Day.
Cheng Cheng Kung Landing Day (Taiwan, 1661)
Hari Raya Haji Day (Singapore)
Ming loyalist Koxinga's Landing (Taiwan)
Birthday of Sultan of Terengganu (Malaysia)
Koninginnedag/Queen's Night (Netherlands)

(Photo credits: tree, netglimse.com; Shrimp Scampi, dangerous and beautiful.com; laughter, daily spiritual tools.blogspot.com; National World War II Memorial, weblogs.dailypress.com; Jerry Seinfeld, iprofilez.com; Middle Age marriages, montgomeryschoolsmd.org; Greenery Day, Himeji castle, bugbog.com; Dancing people dressed in orange on the canals of Amsterdam during Queen's Day in 2007)