I wanted to get a DS just to get a Kanji Kentei game, lol. I realized it was a waste of money just for one game, so I've decided against it (for now hehe).
Since we're sharing:
These are the sites I typically use (nothing fun and game like, hehe)
1.
Skritter: you use your mouse or a wacom pen/tablet to write kanji.
2.
Renshuu: Lots and Lots of customizable vocab, grammar and kanji quizzes.
3.
Japanese Online Institute: live online japanese lessons using mic and/or cam. They also have a few quizzes for registered students.
3.
Kanji Damage: Basically a list of kanji in an order that's supposed to make it easier to remember. It has all the usual information plus information and "real life" usage and mnemonic sentences.
4.
Conversation Exchange: A site used to get a pen pal or find a language exchange partner.
I sometimes use
Livemocha. Everything else I do involves pen, paper and real books.