Japanese Language Reading Tutorial System was developed to help native Japanese speakers as well as non-native Japanese speakers to learn to read Japanese at their own pace.
As well as an on-line dictionary in Japanese, English, Slovenian, Spanish, Dutch and German, there is a reading resource bank with explanations in Japanese, English and German.
The reading materials are graded by star -
1 star = easy
2 stars = more difficult than 1 star
3 stars = more difficult than 2 stars
and they are mostly related to "all things Japanese" and so are very helpful for the comprehension part of the JLPT exam.
There are also some multiple choice quizzes in Japanese - I think that these are quite difficult!
