I love my Wonderswan!
That said, I'll delve deeper: The Wonderswan is a handheld console produced by Bandai, and thus far, only available in Japan. Having only about 15 % of the market share of all handhelds in Japan (the majority being gobbled up by Nintendo's Gameboy Advance), it still manages a suprisingly good showing.
First came the WonderSwan, a b/w handheld console with plugin modules, powered by a single AA battery. It was followed up by the WonderSwan Color, which also started a cooperation with Square (more on that later). Finally, in June 2002, Bandai released the latest model, the SwanCrystal (available in blue-violet and wine-red), featuring a superior (2.8 inch) TFT color display (sharper, clearer, bigger and better visibility), as well as a 15-hour battery-lifespan and weighing just 95 grams.
The biggest boost for the Swan came in 2000 when Square released their classics Final Fantasy, Final Fantasy II and Romancing Saga for the WonderSwan Color, making it the number 1 console for retrogaming. Lately, other licenses have made their way to the Swan, such as games for such series as One Piece, Inu Yasha, Gundam, Shaman King, X, Digimon or Super Robot Taisen, furthering the popularity of the Swan, and boosting sales (Last month it outsold the XBox 4:1.).
The Wonderswan also is the only handheld console for which a developers toolkit (the Wonderwitch) is available for regular users, enabling you to code your own apps and games.
The future does indeed look good for the Wonderswan, and even though it will probably never beat the Gameboy Advance in sales, it is still a damn good console albeit with a somewhat silly name.