I learn German since 30 years - I love it, and, living in Germany, I get everyday something new. My unclosed gap was, as for many other, German gender words (der, die, das). So I wrote a Chrome extension, which displays deutsche Artikel and word meanings on any website, inclusively Gmail and Hotmail editors. Just highlight a word or a part of a word with mouse or keyboard and hit the shortcut - extension gets data from Duden and displays it in a small tooltip.
Feel free to use it: it is free, doesn't gather any user data and doesn't slow your browser. If somebody means it could be worth publishing it in the main QA part, just say - I'l do it with pleasure.