http://japanese.about.com/
It's a very nice resource. It gets you started with all the basics, answers most common questions, teaches you hiragana, katakana, has basic Kanji lessons that get you started with about 60 Kanji, and has an archive containing some 1500 Kanji characters. It also has many grammar related articles and basic setting-specific scenario lessons (e.g., at the restaurant, etc.) to enrich your vocab.
However, the site is bad at teaching grammar and -real- language skills. It won't hurt to read some grammar lessons from about.com, but your main grammar guide should be this:
http://www.guidetojapanese.org/learn/grammar
Tim Kae's guide teaches you Japanese grammar in a very intuitive way; it teaches you how grammar computes in a Japanese person's mind. It doesn't just dictate -how- you say something, but also -why- it is this way, making things a lot easier and saving your ass from a lot of blind memorization of fake "rules" you find in conventional Japanese books.
I hope that helps.