6th: Waitangi day - New Zealand's national day. Commemorates the signing of the Treaty of Waitangi.
Thursday before Ash Wednesday: Fasnacht in parts of southern Germany and Northeastern Switzerland - Colourful street carnivals to ward off the winter spirits, featuring costumed brass bands. Takes place in most towns
Late January or early February: Chinese New Year, celebrated in China, Singapore and anywhere where there are large concentrations of Chinese
Late January or early February: Korean Lunar New Year (Seollal), South Korea
Late January or early February: Vietnamese New Year (Tết), Vietnam
Late February or early March: Carnival in Brazil and others. The precise date of carnival is 7 weeks before Easter, which is moveable itself (the first full-moon Sunday after 21 March). Instead of relying on your own astrophysics skills, take note: Ash Wednesday for the next years will be 01 March 2006, 21 Feb 2007, 06 Feb 2008, 25 Feb 2009 and 17 Feb 2010.