Read this if you don't know how ----Computing in Japanese
Grammar
Jim's Basic Japanese Grammar Summary
Tae Kim's Grammar Notes- Great site!
Check out this site from Nagoya. Lots of grammar practice.
Tons of Fun practice from Genki Book
Vocabulary
Language Guide Vocabulary Practice
Fun ways to learn
Learn Japanese by Manga with Audio
Japanese Pera Pera Penguin articles from Yomiyuri Shinbun (5 minute Japanese lessons.)
Current events
Dictionaries and Translating Sites
For reading Japanese webpages or study, try Rikai.com or Reading Champ. Both of these sites are amazing!
Jim Breen’s Japanese Dictionary Page Reading Tutor Dictionary
There are other dictionaries but a dictionary is only as useful as you are able to use it. If you just search for a word and don't cross check it you could end up with a really wrong word.
If you want to know a word in Japanese, look it up in an E-J dictionary. Then check it again in a J-E dictionary!
Jekai Japanese Dictionary Project
Japanese After High School
CSU Sacramento
Butte College- currently does not have a Japanese instructor