I'm a big believer in using virtual flashcards as a way to expand one's vocabulary, and tried out loads of apps and websites at the beginning of the year. I first created a whole series of flashcard sets for my students on StudyBlue (you can find them here), but lately have been using Quizlet because it's a bit more user-friendly and has some nice games (click on 'Choose a Study Mode' to try them out). Quizlet also allows you to embed your flashcard sets, which is what I've done below for the one based on telephone vocabulary and expressions. I'm not a great fan of computer-generated voices, but the Quizlet one is not too bad and you can always turn the volume down. You could, of course, record your own voice, as I did on some of my StudyBlue sets, but that is incredibly time-consuming ...