Sites to Remember
1. JGram.org
This site’s strong. It looks like some beepworld stuff from the late 90s, but it’s got lots and lots of grammar with notes and examples, and it’s ordered by JLPT difficulty. If you know all the grammar presented on this site, you know a lot. Sadly, it’s really hard to look at, I don’t think there are two opinions about that.
It’s official since 1997 and it certainly looks that way; he also forgot the hyphen between “Tim” and “Sensei.” Be that as it may, it’s the inner values that count and its contents aren’t bad at all. It’s not the first site you should visit when you wanna know something about Japanese grammar, but it’s a site you should check out when you failed to understand something. It’s always good to read different approaches on rather difficult subjects.
3. Jisho.org
Yes, I named that one a long time ago already, but that was before they revamped the site. You can now search for kanji by radicals, which is a big help if you run across something that you know neither the meaning, on-, or kun-reading of. Works great on mobile devices, too. Definitely a must-have bookmark for anyone involved with Japanese. I wished they would provide us with (free) mobile apps too.