[sequoia]

http://noexcuselist.com/everything See the "Languages" section.

I've used duolingo for Spanish review; it's pretty good. Honestly the best thing about it is the UX: you get little bite-sized exercises you can go thru as fast or slow as you want, review, etc., so it's easy to squeeze into a 10-20min/day block. The main weaknesses are a) the examples are arithmetically generated so sometimes you get "My horse only eats milk" or something as an example sentence (it's usually pretty good tho), and b) you don't get a deep grammar review, it's just lots of little examples & practices. The latter point could be seen as a "pro" depending on your learning style.