Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.
Memrise - Learn a new language with games, humorous chatbots and over 30,000 native speaker videos.
Cram - Cram is an app for Android, Windows and Apple devices that allows you to search for flashcards in a range of topics to study for an upcoming test or to learn new information. Read more about Cram.
Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.
Simply Learn Languages - A phrasebook of 50+ languages for traveling (with audio)
Discovery FlashCards - Discovery FlashCards is a unique free program that can help you study.