Quizlet is the largest flash cards and study games website with over 9 million free sets of flashcards covering every possible subject. It's the best place to play educational games, memorize vocabulary and study online.
How can an iPhone, iPod, or iPad help a child to learn? Take a look at the Apple Apps for Education. If you want to learn "it", there's probably an app for that.
This site has some great Internet treasure hunts you can use to introduce students to some excellent web resources. A variety of other teacher tools are included.
This is my favorite site for creating online quizzes and flashcards. There is an annual fee, but there is also free content. After entering a data set, you students can play a variety of educational games to review the content you've created.
Many schools now use this site to help students review key concepts in math and do some drill and practiced to improve their skills. It is broken down by grade level and standard.
Make a crossword or word search to help students learn vocabulary. Puzzles are printable, and many can also be played on line and linked to your class webpage. Draw from the puzzles already included. You don't have to recreate the wheel.