AcchaNi is a program that assists with learning Japanese. It is cross-platform, requires no special Japanese fonts or encoding, has built-in hiragana input, and supports iterative learning modes.
The Accha Nihongo quiz program now features "leveling" capabilities: after mastering a small group of kanji, you "level up" and are presented with a new group of kanji. When exiting the program, Accha Nihongo automatically remembers what level you were on, and allows you to continue from this point the next time you play. The kanji display has also been completely overhauled, and now includes dictionary definitions of the different readings, as well as radical/element information to aid memorization.