None that I know of.
Listening is relatively easy (especially for genre and kids' shows), but reading is pretty hard.
What I do is run the text through a good dictionary site (I use WWWJDIC's text glossing feature). The good thing about that is that it catches idioms pretty well. You would still need to have rudimentary knowledge of hiragana/katakana AND Japanese grammar, though, to get anything remotely accurate from it.
I've had some problems with some Japanese blogs though where the text can't be copy pasted. That's why I had to learn constructing kanji from radicals.
If you have the time I would really suggest at least getting a Japanese grammar book and memorizing hiragana and katakana anyway. Japanese grammar actually makes more sense than English does.