I have used flashcards on/off in my language studies. Has it helped me? I would like to think so. Many learners are quite negative when flashcards are brought up in discussions, but a little imagination can go a long way.
Martin Sketchley, who works as an English teacher, has compiled a list of ways in which you can use flashcards. Who knows, you might even end up finding them entertaining!
Most of them can easily be adapted to a language exchange so there is no need to attend a class to make it work.