Kansai (関西) is the western region of the main Japanese island of Honshu, second only to Tokyo's Kanto in population. The area is also known as Kinki (近畿), literally "near the capital" (referring to former capital Kyoto), and its three big cities — Kyoto, Osaka and Kobe — as Keihanshin (京阪神).
Differences between Kansai and Kanto (the eastern region dominated by Tokyo) are slight but numerous. Kansai people speak a distinctive dialect of Japanese, use lighter-colored soy in their cooking, ride on the other side of escalators and are renowned for humor and their love of food.
Hyogo - the largest prefecture in Kansai, stretching from coast to coast and covering Kobe and Himeji
Arima Onsen - historic hot spring town just across the hill from Kobe
Horyuji - temple complex housing some of the oldest wooden buildings in the world
Lake Biwa - placid marshy lake nice for a quick getaway
Mount Hiei - headquarters of Tendai and protector of Kyoto
Mount Koya - mountaintop headquarters of the Buddhist Shingon sect
The Kansai dialect (関西弁 Kansai-ben) is Japan's liveliest, and largest dialect group after Kanto's Japanese dialect group collectively. There are many subdialects, ranging from the effete Kyo-kotoba (京言葉) of Kyoto's courtiers to the gruff but imaginative gangster slang of Osaka, much favored by Japanese comedians. Some notable features include the negative ending -hen instead of the normal -nai and the use of akan instead of dame for "No way!".
That said, most Kansaites are perfectly conversant in standard Japanese, so knowledge of the local dialect is by no means necessary, but even a few words will be appreciated. The canonical Osakan greeting is Mōkarimakka? ("Making money?"), to which the canonical reply is Botchi botchi denna ("Well, so-so"); trying this out on a friend or acquaintance is guaranteed to produce a surprised smile, and make you look like a kettai (funny, strange) or omoroi (funny) guy.
International flights to the Kansai region land at Kansai International Airport. The primary domestic airport is Osaka's Itami Airport (officially called Osaka International Airport even though there are no longer any international flights), although a new airport opened in Kobe in 2006.
Most of Kansai's regional transportation companies have tied up to offer the ICOCA tickets, which can be used on pretty much any train, subway, monorail, cable car or bus in the region. The Nankai and JR trains from Kansai Airport are also included, and you can buy your card or pass at the airport's train station.
The ICOCA card  is a contactless smart card that can be used on JR West, JR East (Tokyo) and most private rail and bus companies in Kansai and Chugoku (Okayama, Hiroshima). Cards are available at ticket vending machines in train stations for ¥2000, including a refundable ¥500 deposit. More money can be added at the same machines.
The Surutto Kansai magnetic card is similar to ICOCA, but it doesn't work on JR and is not rechargable, making it pretty much obsolete.
The Kansai Thru Pass can be purchased as a two-day (¥3800) or a three-day (¥5000) pass. It is valid for two/three separate days within the validity period which is printed on the back (usually a couple of months). It can be used on most non-JR trains and buses (and even some cable cars) in Kyoto, Osaka, Kobe and Nara with the notable exception of JR trains. The service area extends south to the Kansai International Airport and the city of Wakayama and southeast to Mount Koya (Check the Area Map on the webpage for details). In addition to free transport, these tickets offer a series of small discounts to temples, museums and other attractions in the region. Be aware that you'll have to travel quite a bit to make them pay off. (Note: You might be asked to show your passport when you purchase this card.)
JR-West also offers the Kansai Area Pass, which costs ¥2000/¥4000/¥5000/¥6000 for 1/2/3/4 days respectively and is valid for unlimited travel on JR standard and Haruka limited express trains (non-reserved seats only). The area covered is approximately the same as for the Kansai Thru Pass above. There is also a more complicated route-based JR 4-day pass for different routes in the Kansai area called the Kansai Passport.
With its political and geographical significance in the history of Japan, the region of Kansai possesses three quarters of Japan's "National Treasure" buildings, half of its "National Treasure" artworks, as well as five UNESCO World Heritage Sites, making it an unmatched destination for heritage tourists to Japan.
Kyoto and Nara are both ancient capitals of Japan chock-a-block with temples and historical sites.
Banded together as the Sacred Sites and Pilgrimage Routes in the Kii Mountain Range, the shrines of Yoshino, Mount Koya and Kumano are UNESCO World Heritage sites.
Kansai cooking is subtly different from the Kanto style, although the average short-term visitor is unlikely to spot many differences. Perhaps the most visible differences are a tendency to use light-colored soy instead of dark, especially in soups, and a preference for thick white udon noodles over the thin buckwheat soba noodles of eastern Japan.
Some famous Kansai dishes include:
sabazushi (鯖寿司 mackerel sushi), Battera of Osaka, sabazushi in Kyoto, or kaki-no-ha zushi (柿の葉寿司) from Nara are local variants of this type
okonomiyaki (お好み焼き), variously described as Japanese pizza or pancakes. Although Hiroshima also makes a strong claim for this name, they are in fact reasonably different from each other. (Hiroshima style tends to come cooked on a pile of noodles.)
takoyaki (たこ焼き) is the common name for the fried balls of octopus and batter. Akashiyaki (明石焼き) from Akashi City area is recognized as the origin of the more famous Osaka-style takoyaki. As opposed to the Osaka-style being served with dark and thick sauce on it, Akashiyaki are eaten without sauce but dipped into clear soup. When visiting takoyaki bars, the various fillings mentioned are generally substituted for octopus, rather than being an addition.
beef (和牛), there are famous beef brands; Kobe beef (神戸牛), Matsusaka beef (松阪牛), Tajima beef (但馬牛) and Omi beef (近江牛).
udon (うどん) is the popular noodle in Osaka instead of soba in Tokyo. Another udon area, Sanuki in Shikoku, is famous for delicious noodles, while Osaka is famous for delicious soup.
Kansai is sake country, with Nada (in Kobe) and Fushimi (in Kyoto) alone accounting for 45% of the country's production. Kobe in particular is a good place to tour sake breweries, many of which are open to visitors.
This is a usable article. It gives a good overview of the region, its sights, and how to get in, as well as links to the main destinations, whose articles are similarly well developed. An adventurous person could use this article, but please plunge forward and help it grow!