Curriki, should be on your list for repeat visits. At the home page their billing reads: The non-profit empowering educators to deliver and share curricula. Curriki made the Top 25 Web sites for Teaching and Learning 2009 generated by AASL, the American Association of School Librarians.
In their about section they state:
Curriki originated from the idea that technology can play a crucial role in breaking down the barriers of the Education Divide---the gap between those who have access to high-quality education and those who do not. ... A non-profit organization, Curriki is the leading K-12 global community for teachers, students and parents to create, share, and find open learning resources that improve teacher effectiveness and student outcomes.
Across the top of the home page are a series of tabs: contribute+publish resources, connect with teachers, interactive resources, and full courses. There are a series of tutorials on making contributions to Curriki, contribute a file attachment, create a resource using a template or create an HTML resource from scratch.
Users can get and give constructive feedback on current curriculum resources, join or start a group with a specific goal, read how others are using Curriki and get the latest news by reading the Curriki blog.
If you are looking for a new take on a lesson that you are currently teaching, have an idea upon which you wish to expand or have a great lesson that you want to share with others than Curriki is the place for you.