Learn new language while you are reading emails, reading news on the web. I had an idea that I had worked on quarters back called Lingo Inline. Developed an extension for outlook that will read email and modify few words in new language you are trying to learn.
Why email? Because I am on email always and hooked to it.
Extension to outlook? Because outlook allows building extensions and I am on outlook for my emails.
How it works? It used the outlook API. Allows read access to the email with the extension. I pick up few words from the email and show in the extension tab.
Video from when it was developed -