MemoryLifter is a freeware program which displays flashcards. Although it’s not specifically for English, there are English modules and you can create your own set of materials for your students allowing them to study and learn the items appropriate for their level and needs.
The program can use not only standard text flashcards but also images and sounds to enhance, speed up and improve learning. Free flashcard sets for English include opposites, medical terminology, architectural terminology and spelling. However, teachers can create their own flashcard sets to add to these.
There are several useful features, not least the fact that the software is authorable so you can add images specifically for your class.