/inside
. about/projects
. overview/outside
. fm. resources for studying and practicing Japanese
Please note: Most of these resources work fine for beginners. However please keep in mind I'm an intermediate learner, and these are sources that I personally find useful. Basic kana and kanji knowledge is needed in most cases.
websites
Lang-8The Japanese Page
Has a lot of very useful tools, information, fora and more, all about Japanese.
The Japanese speaking community & Correct Japanese @ LJ
If you've got a Livejournal, these are two excellent communities to keep on your friends list. You can ask questions about the Japanese language and can have your Japanese corrected. Even just observing the posts is very useful to improve your Japanese.
All Japanese All The Time
I don't believe what this guy is doing is suitable for most people. However, he's writting some quite interesting stuff, it's worth reading.
webtools
RikaichanFurigana Injector
Firefox tool. Adds furigana to kanji. Doesn't always look pretty, but is reasonably useful. Personally I don't use it often though, I usually go with just Rikaichan.
dictionaries
Kanji sonomama DS Rakuhiku JitenLangenscheidt Pocket Dictionary J-E/E-J
Not the best dictionary out there, but good enough, cheap, light-weight and easy to use.
online dictionaries
WWWJDIClearning tools
Ankibooks
Minna no nihongo