Recs.
Updated
Duolingo is a website/app where you can take courses in several languages. Each lesson uses a variety of different learning methods to help make sure the lessons stick.
SpecsUpdate
Pros
Pro Motivates through creative gamification
Progress is measured gaming-like by gaining XP, leveling up and knowing how many words are learnt. Also, lessons have a limited amount of lives, which you must preserve to pass the lesson.
They use other creative gamification techniques to keep you motivated such as making wagers and improving your position on the leaderboard.
Pro Friendly, active community
There is a discussion board available on the site, and a really active community on reddit in r/duolingo (30k + members). Everyone is friendly and happy to help or offer support.
Pro Frequently adding new languages
You can check out the courses page to see what languages are "hatching" (being developed) and what languages are in beta.