Searching vocabulary in another [language]
I think one of the problem when reviewing the vocabulary is that sometimes I can only remember the word in English. So I think an option to search through the vocabulary or in a different language that the vocabulary is in would be helpful for all users.
This would make the vocabulary work a bit more like a dictionary or thesaurus, and be easier to use.
For example if I want to find the French word for fly, i must remember it is 'mouche' otherwise I have no hope of discovering it without clicking every word.