High Def Teacher is a collection of resources for teachers, submitted by teachers.
The site resources are organized into topics for easy searching. There is even a "top rated" and "new" topic to make it easy to find great resources. There are also sites of the week for each category and some articles about education posted. Each resource is rated by users, which gives you a preview of the quality or usefulness of the resource.
Topics: Top Rated, New, General, English, Math, Science, Social Studies, World Languages, Electives. Some of the topics, such as Science, also have subtopic categories.
This is another great site to find resources to help improve teaching and learning.