Tadashii Kanji Kakitori-kun
If you're new to Japanese and want to learn some cool kanji, this is NOT THE TOOL FOR YOU! You can learn the stroke orders and readings for the kanji, but you won't know what they mean or some examples of words they're used in... Chances are you won't take much from it.
However, this can be solved very easily. Download this free program:
http://www.physics.ucla.edu/~grosenth/c_download.html#SIMPLE
You can look up kanji meanings, readings, radicals, and much more in it. It also has a very full dictionary with both kanji and kana. Combined with this, Tadashii Kanji Kakitori-kun is a very useful tool. If you're using DS homebrew, I also recommend looking up DSLearnJ, a simple flash card program with Japanese character support (you can fully customize the flash cards using the above program I linked to).
Lastly, I use this for a list of kanji in the order Japanese children learn them: http://japanese.about.com/library/blkodarchives.htm
Trust me, you should learn them in order even if some of them seem "useless" to you. It might seem random at first, but they must have planned and organized it very well since you often get the same on-yomi (Chinese-based readings) on kanji in a row, making it easier to memorize them.
My Japanese Coach
DO NOT BUY THIS!This game is pretty much useless. Do not waste your money and do not give those half-assed producers a profit. There are numerous mistakes and the game doesn't allow you to proceed unless you do things their way (the WRONG way). You will be teaching yourself that wrong is right and right is wrong.
The "proficiency test" at the start is a total joke, using words like "samurai", "anime", and "ninja". They teach you a bit of vocabulary, which is good, but there are many flaws in the lessons. In the middle of a lesson, they'll start discussing something you already covered; they show you the examples from old lessons that have nothing to do with the current lessons.
Understanding verb conjugation is an extremely important part of learning Japanese (or any language), but the way they teach you is extremely difficult to remember, and they refer to it in an equally difficult way in later lessons. Rather than saying something like "tabemasu" (the polite form of "taberu", "to eat"), they'd say "base 1 + masu"... And you have to remember their retarded base 1 to base 7 or whatever in order to conjugate anything. It's all very, very stupid.
I thought the game seemed kinda useful at first, but trust me, it's a waste. It's easier to learn from free resources on the internet than it is to learn from that heap of junk.