is there a vocab list for what one has learned? this would be very handy for review...
I teach adult immigrants to speak English. I do not hand out vocabulary lists because I expect my students to keep notebooks with their own lists that they write. Repetition is vital to learning a new language. It will help you to learn the words if you create your own vocabulary list. There is no way for anyone else to keep track of the words you are familiar with and the words you, personally, still need to study. Create your own list. Create your own flashcards. Use a spaced repetition program. The more you use the language, the more you learn.
I couldn't find a vocab list, so started adding all the new words and phrases I come across into Evernote notes. As silverapricot has mentioned, Workflowy seems to be a good choice too. Anyway, I hope the Duolingo team would implement this current vocabulary list feature.