NEW This is a good site for making Bingo Cards, Domino cards, and memory cards for shogakko visits etc. I like this because you can customize the themes and accompanying pictures. (e.g. add a Pokemon theme etc) Here
Good site for helping kids to learn how to write. Make your own worksheets with this tool.
Site for Adult ESL classes
ESL BLUES - many activities
Outstanding elementary school clip art
Royalty Free Clip Art
Some good grammar explanations and exercises
Looks interesting, but haven't had much time to check it out yet.
"Have a warmup ready in one minute please" - new horizon activities
A paid site, but good worksheets and flashcards for kids
Word Up - A great game for small classes, adult ESL and English clubs
One Stop English is a popular site among JETs with many ready to use worksheets.