Cheongsam Cantonese for "long dress." A traditional Chinese dress, originally Manchurian qipao ("banner gown"). See Chinese Fashion (which also includes this History of Cheongsam), Qipao / Cheongsam, TV Tropes, Wikipedia, or Everything2.
Dou li Chinese word for a conical straw hat, worn for protection from sun and rain. It's most commonly associated with workers in paddy fields. The Korean word for such hats is satgat, which is mostly worn by Buddhist monks. The Vietnamese word is non la ("leaf hat"). The Japanese word is sugegasa (see also kasa). See Wikipedia or TV Tropes.
Gaku-ran Military style uniform worn by Japanese schoolboys. See Wikipedia.
Geta Japanese sandals, traditionally wooden, though modern ones may not be. They're raised on two strips. See The Geta Page, JapaneseKimono.com, Wikipedia, or Everything2.
Gi Clothes. Also short for keikogi.
Hakama are a type of outerwear, pleated pants or skirt, worn over a kimono. See JapaneseKimono.com, Wikipedia, or Everything2.
Happi An overcoat traditionally worn by shopkeepers, which is now often used as a short robe for festivals, etc. See JapaneseKimono.com or Wikipedia.
Kanzashi Hair ornaments (such as combs, hairpins, or cloth flowers). See Wikipedia, Everything2, or TV Tropes.
Kasa Any of several types of traditional Japanese hats. A sugegasa is basically the same as a Chinese dou li, or conical straw hat, used by farmers. Other types of kasa might be worn by Buddhist monks, or samurai, or ronin, or dancers, etc. See Wikipedia.
Keikogi Training clothes. Worn when practicing martial arts. Also called "gi" or "do gi." See Wikipedia or Everything2.
Kimono means literally "clothing" or "things to wear," though of course we have a specific image of kimono as a particular type of Japanese clothing. Kimono are today usually only worn on special occasions. See JapaneseKimono.com, TV Tropes, Wikipedia, or Everything2.
Nemaki Sleepwear. See JapaneseKimono.com.
Obi A sash worn with a kimono. See JapaneseKimono.com, Wikipedia, or Everything2.
Qipao See Cheongsam.
Seifuku Uniform. See Everything2.
Sera fuku Sailor suit, which is worn by Japanese schoolgirls and is often seen in anime. See TV Tropes or Wikipedia.
Shibori See arts page.
Shihakushou I'm not sure if this word actually is used anywhere except the anime Bleach. In that, it refers to the uniform worn by most Soul Reapers, which consists of a white undershirt, black kimono and hakama, and a white sash (apparently not an obi, not that I know the difference).
Tabi Japanese socks with a split for the big toe, so that they may comfortably be worn with sandals. (Tabi can also mean "journey.") See JapaneseKimono.com, Wikipedia, or Everything2.
Tatami A type of zori sandals made of straw, like tatami mats (see stuff page).
Uwabaki Indoor slippers or shoes to wear after removing your outdoor shoes in the genkan (see stuff page). I think this word only applies to slippers worn at schools... See TV Tropes.
Yukata An informal summer kimono or bathrobe. See JapaneseKimono.com, Wikipedia, or Everything2.
Zori Any Japanese sandals with a flat bottom. See JapaneseKimono.com, Wikipedia, or Everything2.
Chonmage A Japanese hairstyle mainly associated with the Edo period (history page). The pate was shaved and the remaining hair was tied into a topknot. In modern times, only sumo wrestlers (martial arts page) wear chonmage, but without a shaved pate. See Wikipedia.
Ganguro Black face. A trend in the '90s, where Japanese girls would imitate the look of California beach-bunnies by bleaching their hair and getting deep tans, as a rejection of the traditional Japanese feminine ideal. The trend was later revived as manba. See Wikipedia or Everything2.
Harajuku girls An eclectic style, or rather any number of different fashion trends might fall into this category.... See Wikipedia.
Lolita is a fashion trend which includes various styles, most notably Gothic Lolita (GothLoli, Loli-goth) and Sweet Lolita (amaloli). Basically, it's about trying to emulate Victorian fashions, and also look childishly cute or even like a Victorian doll. Of course, as the name Lolita suggests, there can sometimes be a sexual aspect to the childish nature of the fashion trend. See also lolicon (sexual terms page; discretion advised). See Avant Gauche, TV Tropes, Wikipedia, or Everything2 (Gothic; Sweet).
Manba Short form of "yamanba," which means "mountain hag." It's a more extreme version of ganguro. See Wikipedia or Everything2.
Odango A hairstyle with two spherical buns, sometimes also with pigtails hanging down from each bun. There are various anime characters who wear their hair this way, most notably the title character in Sailor Moon. The name of this hairstyle comes from Japanese dumplings called dango (foods page). See also ox horns. See TV Tropes or Wikipedia.
Ox horns May sometimes be called "bao bao," bao being the Chinese word for "bun." Similar to Japanese odango, but it never includes pigtails. Typically, a man would have one hair bun and a woman would have two. (Buns are sometimes covered by some kind of cloth, but I've been unable to learn whether such an article of clothing actually has a name.) The ox horn hairstyle is worn by Chun Li from the "Street Fighter" games and movies, as well as various anime characters such as Tenten from Naruto, Momo Hinamori from Bleach (who has a single bun, which always seems to be covered), Li-en from Zatch Bell!, etc. See Wikipedia.
Zettai Ryouiki "Absolute territory." Refers to the area of exposed thigh between a girl's skirt and socks or stockings, or possibly boots (though the term is only applicable if the top of the socks/boots are above the knees). Very fetishy. See TV Tropes.
See also: culture page, store links (under apparel) and tek's links: stores (under international merchandise)