Lesley University has a very extensive list of elearning resources and references. Search by topic, grade level, subject, and even publisher to find exactly what you are looking for.
With cacoo, you can make diagrams in real-time, allowing simultaneous collaboration. It allows you to easily create diagrams and seamlessly insert them into wikis, blogs, and lots of other documents.
This is hands-down the best Spanish teacher reference I have ever found. Virtually endless information to sort through, yet it is all very well-organized.
This website is centered around helping teachers integrate technology into their curriculum thoughtfully. It also lets teachers interact with each other to build a support network. The website is very organized, it is easy to navigate, has a tone of information, and the concept is explained very well.
This site is great for finding articles on all kinds of topics. Very little to no advertising. Might have too many articles to sort through, so you have to pre-search for students.
Teachers' Domain has a ton of resources for students, and can be accessed by students, if they sign up for an account. The teacher can organize students into individual classes and create folders for students to access what it is you want them to utilize. There are great simulations, activities, and videos for students to explore.
Teachers First offers teachers a large amount of resources to use in the classroom including current trends, lesson plans, information for new teachers and experienced, and even tips to keep parents involved. Lots of forms and worksheets are already created and can be modified.