This list is FAR from inclusive. If you want to see everything available on the web to help teachers, there are plenty of places to look. Web 2.0/21st Century Tools (a wiki put together by David Kapuler) is one that includes an exhaustive list of tools, and what they do. This list contains tools that I have personally used, and have found easy to use, and that I think other teachers will find useful. If you know of a tool that meets these criteria (you've used it, it's easy to use, and useful for teachers) please let me know about it so that I can add it to this list :)

Printables (worksheets, game boards, templates, dice, cards, activities)

Find free images and edit them

Find free clipart

Create projects using images

Find free music and edit it

Create simple animated videos

Create graphics from text (word clouds and banners)

Help with pronunciation

Learn how to use online tools (tutorials)

Video tools

Start a blog for you or your class

Digital Projects

Dictionaries for learners

One-Stop EFL sites (places to get lesson ideas and collections of resources)