http://geoguessr.com/ is a great site to review geography and explore the world. There are numerous ways you can teach geography using this tool. On it's surface it's just a geography guessing game, but a teacher can expand on this game by having students examine physical features, culture, and climate by looking at this site.

www.quizlet.com is a great site for students to review vocabulary. Many sets already exist or you can create your own. Students are able to review by giving themselves quizzes or playing games.