I stumbled across this web site and I thought I should share.
Its a collaborative community of sentence translations. Its kind of awesome. Anyone can post a sentence and anyone else can come in and post a translation. English and Japanese sentences are abundant. Its a great way to identify new vocabulary and see grammar in action with a relevant translation.

Check it.
Contribute.
Here is a link with a quick video that explains how the site works:
http://tatoeba.org/eng/

Looks interesting. I need to take more time to look into it after the JLPT.

By the way, there's no Mycroft plugin for the site, so if you want to add it to your Firefox search bar, this plugin is handy:

https://addons.mozilla.org/en-US/firefox/addon/3682/

If you right click on the site's search box, and use "Add to search bar" after installing the plugin, you can add it to your drop-down search box plugins.