That way you get the correct words for the language you are trying to learn but ignore errors in the language you already know.
Any volunteers to make this extension? :)
I used to read business and tech news in French, but it was frustrating because most of the articles were rehashed from things I read hours (or days) before in English, and I try to keep the S/N ratio of my feed reader as high as possible. The feeds I read in French are mostly related to local news, European politics, music, art, cinema, local events, etc.
Can't remember his name or site though.
And obviously it's not a perfect tool, but it's great to learn assorted new nouns and things like that. I've learned a few things in German since I turned it on.
For learning without having to do something else, I'd recommend:
* Turning on subtitles in the target language for all films you watch.
* Listening to web radio when you're walking/commuting (if you have a smartphone/dataplan). Depending on the language, there are even programs in which the reporters speak slowly and provide a transcript (example: RFI français facile for French, Klartext for Swedish).
* Buying bilingual books (where the English is on the left and the other language is on the right).
This extension probably works best for those with some degree of acquaintance with the target language, if only for the errors you spot.
I think it's much, much more effective to just read a newspaper in the language you want to learn and use a dictionary. It's not as easy, but you're not going to expose yourself to bad grammar that you'll automatically pick up and have to unlearn later.