Word Ahead is one of the best vocabulary-learning sites I’ve seen for advanced English Language Learners and mainstream students.  It uses SAT words, and shows the word and representative image, plus provides audio support for text showing the word being used in context.  It’s on The Best Sites Where ELL’s Can Learn Vocabulary list.

They just launched Word Ahead For Teachers. It has a number of features, including the ability to create personalized vocabulary lists.