Recs.
Updated
Duolingo is a website 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, and leveling up. 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.
Cons
Con The hype in the community creates false ideas about what level Duolingo gets you to
Duolingo is a good tool for a beginner, and a good supplement to other resources. But it cannot get you from zero to understanding natives, tv, and books; and their "do the reverse tree and just speak" is usually not the correct answer to "what should I do after finishing the tree".
Con The health system on the IOS app disrupts learning
5 mistakes and you're out, unless you pay, wait several hours, or use a special review that currently doesn't let you choose what to review. Especially terrible if you're learning multiple or more difficult languages.
Con Available languages are predominately European
Duolingo teaches 23 languages from English at the moment: Latin American Spanish, French, German, Italian, Portuguese, Dutch, Swedish, Irish, Turkish, Danish, Russian, Norwegian, Esperanto, Ukrainian, Polish, Welsh, Greek, Romanian, Hungarian, Hebrew, Swahili, Vietnamese and Japanese (the last currently only on the app). Popular non-European languages such as Mandarin and Arabic are not currently available (although Korean and Indonesian are in development).
Recommendations
Comments
Out of Date Pros + Cons
Con No foreign keyboard on screen
Sometimes you have to translate words from English to the language you are learning... without a foreign keyboard on screen. For example, if you are learning Russian, you must change your keyboard settings (in the system settings) and guess which key is the correct one.