Phrasalstein, developed at Cambridge University, is a
Duolingo is a free service that aims to help you learn Spanish, French, German, or Portuguese. Duolingo offers mobile apps that allow you to practice a new language anywhere you go. The Duolingo mobile apps and website provide a variety of translation activities to help learn to you read, listen to, and translate words and phrases. The activities include looking at pictures that are representative of words and phrases. After reviewing a couple of pictures students are asked to type translations. The app gives immediate feedback to students.
Forvo is not an app, but it is a website worth mentioning on this list. It can best be described as an audio wiki for word pronunciations. One of the problems with learning to speak a language that is not phonetic is trying to figure out how to pronounce the words. Forvo hosts hundreds of recordings of word pronunciations by native speakers. Along with word pronunciations, Forvo provides some basic demographic information about each language. Forvo's content is user-supported and user-generated. New pronunciations are added on a regular basis.