TransOver

Hover, click or select to translate (with text-to-speech). Translator.

Translate word (or text selection) from any language to the language of your choice by pointing or clicking at it.

Also you can (enable in options):
- text-to-speech
- reverse translate: from your own language to the language of your choice
- type and translate in a popup
- copy translation to clipboard

Chrome version: https://chrome.google.com/webstore/detail/transover/aggiiclaiamajehmlfpkjmlbadmkledi

Firefox version: https://addons.mozilla.org/en-US/firefox/addon/transover-ff/