ReadDict allows you to keep track of any number of vocabulary lists in several different languages (Russian, German, Spanish, French are available right now). You can highlight sections of text, view translations, and even link out to a mobile-friendly flashcard view for studying vocabulary on the go. The plugin also allows for bookmark management so that you can come back to a a specific point on a long page without having to scroll through and remember where you stopped off. This is in the very early stages, but it's functional, so I wanted to get it out there for evaluation and educational use. Enjoy!