web-ext-slovnikcz
This is a very simple Webextension to translate a selected word using the http://www.slovnik.cz/ site.
It pops up a modal window with translation from http://www.slovnik.cz/ to get rid of it just click the mouse or press escape.
Install it directly from the chrome webstore
Or for Firefox on the mozilla addons.
It supports only english to czech translation at the moment
Screenshot
