Quizlet keeps track of the words you know and only retests you on the ones you don't.
You can share your vocabulary sets with classmates and get email notification when others make sets for you.
MCJeopardy is a free customizable multiple choice Jeopardy game based in Microsoft PowerPoint. Unlike other PowerPoint Jeopardy games, MCJeopardy keeps score for you. Up to four players/teams can play at one time.
Cramberry helps you memorize things using flash cards. Create cards online, and study them. Cramberry tracks your progress, and helps you focus on the cards you're having trouble on.
Classtools.net provides free, customisable flash templates to embed into blogs, wikis and websites. There is no signup, no passwords, no charges
Fantastic site! Enter spelling lists. Site teaches words by orally spelling the word and using it in a sentence, provides games, and a test.